Fixing TypeCast errors for time based functions.
Fixing TypeCast errors for time based functions.

Several functions were returning floating point startTime and endTime.

As a result, urls like the following would fail.

/render/?target=keepLastValue(sin("sin"))&from=-5minutes&format=json

The resulting error stack looks like...

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py",
line 111, in get_response
    response = callback(request, *callback_args, **callback_kwargs)
  File "/opt/graphite/webapp/graphite/render/views.py", line 126, in
renderView
    timestamps = range(series.start, series.end, series.step)
TypeError: range() integer end argument expected, got float.

Aloomaio/graphite-web,gwaldo/graphite-web,disqus/graphite-web,graphite-server/graphite-web,ceph/graphite-web,AICIDNN/graphite-web,esnet/graphite-web,lyft/graphite-web,piotr1212/graphite-web,atnak/graphite-web,pcn/graphite-web,deniszh/graphite-web,cbowman0/graphite-web,bbc/graphite-web,Krylon360/vimeo-graphite-web,cybem/graphite-web-iow,obfuscurity/graphite-web,DanCech/graphite-web,brutasse/graphite-web,criteo-forks/graphite-web,jssjr/graphite-web,goir/graphite-web,MjAbuz/graphite-web,esnet/graphite-web,graphite-project/graphite-web,lfckop/graphite-web,markolson/graphite-web,MjAbuz/graphite-web,pu239ppy/graphite-web,AICIDNN/graphite-web,kkdk5535/graphite-web,ceph/graphite-web,bruce-lyft/graphite-web,Squarespace/graphite-web,evernote/graphite-web,edwardmlyte/graphite-web,cgvarela/graphite-web,section-io/graphite-web,mcoolive/graphite-web,Aloomaio/graphite-web,mcoolive/graphite-web,evernote/graphite-web,ceph/graphite-web,penpen/graphite-web,SEJeff/graphite-web,cosm0s/graphite-web,Squarespace/graphite-web,graphite-server/graphite-web,mleinart/graphite-web,deniszh/graphite-web,criteo-forks/graphite-web,axibase/graphite-web,graphite-project/graphite-web,krux/graphite-web,jssjr/graphite-web,ZelunZhang/graphite-web,blacked/graphite-web,section-io/graphite-web,Krylon360/evernote-graphite-web,bmhatfield/graphite-web,criteo-forks/graphite-web,edwardmlyte/graphite-web,lfckop/graphite-web,Krylon360/evernote-graphite-web,pcn/graphite-web,synedge/graphite-web,g76r/graphite-web,blacked/graphite-web,dhtech/graphite-web,gwaldo/graphite-web,MjAbuz/graphite-web,ceph/graphite-web,obfuscurity/graphite-web,jssjr/graphite-web,bruce-lyft/graphite-web,JeanFred/graphite-web,jssjr/graphite-web,Krylon360/vimeo-graphite-web,SEJeff/graphite-web,JeanFred/graphite-web,bpaquet/graphite-web,criteo-forks/graphite-web,atnak/graphite-web,johnseekins/graphite-web,mcoolive/graphite-web,g76r/graphite-web,kkdk5535/graphite-web,piotr1212/graphite-web,gwaldo/graphite-web,markolson/graphite-web,drax68/graphite-web,blacked/graphite-web,axibase/graphite-web,kkdk5535/graphite-web,Invoca/graphite-web,brutasse/graphite-web,edwardmlyte/graphite-web,redice/graphite-web,synedge/graphite-web,phreakocious/graphite-web,lfckop/graphite-web,drax68/graphite-web,bbc/graphite-web,g76r/graphite-web,cgvarela/graphite-web,Aloomaio/graphite-web,esnet/graphite-web,atnak/graphite-web,redice/graphite-web,penpen/graphite-web,brutasse/graphite-web,Krylon360/evernote-graphite-web,graphite-project/graphite-web,Krylon360/vimeo-graphite-web,graphite-project/graphite-web,kkdk5535/graphite-web,cybem/graphite-web-iow,drax68/graphite-web,MjAbuz/graphite-web,cbowman0/graphite-web,dhtech/graphite-web,disqus/graphite-web,cosm0s/graphite-web,phreakocious/graphite-web,krux/graphite-web,Krylon360/vimeo-graphite-web,g76r/graphite-web,deniszh/graphite-web,phreakocious/graphite-web,cybem/graphite-web-iow,lfckop/graphite-web,brutasse/graphite-web,JeanFred/graphite-web,ZelunZhang/graphite-web,Krylon360/vimeo-graphite-web,disqus/graphite-web,DanCech/graphite-web,bruce-lyft/graphite-web,redice/graphite-web,goir/graphite-web,johnseekins/graphite-web,gwaldo/graphite-web,Invoca/graphite-web,Invoca/graphite-web,bbc/graphite-web,section-io/graphite-web,jssjr/graphite-web,goir/graphite-web,mleinart/graphite-web,criteo-forks/graphite-web,SEJeff/graphite-web,dhtech/graphite-web,markolson/graphite-web,redice/graphite-web,Skyscanner/graphite-web,nkhuyu/graphite-web,axibase/graphite-web,redice/graphite-web,bpaquet/graphite-web,Skyscanner/graphite-web,edwardmlyte/graphite-web,Krylon360/evernote-graphite-web,dbn/graphite-web,cbowman0/graphite-web,Aloomaio/graphite-web,criteo-forks/graphite-web,goir/graphite-web,dbn/graphite-web,mleinart/graphite-web,pu239ppy/graphite-web,esnet/graphite-web,Squarespace/graphite-web,bmhatfield/graphite-web,DanCech/graphite-web,bmhatfield/graphite-web,mleinart/graphite-web,AICIDNN/graphite-web,pu239ppy/graphite-web,synedge/graphite-web,Invoca/graphite-web,obfuscurity/graphite-web,axibase/graphite-web,zBMNForks/graphite-web,jssjr/graphite-web,dbn/graphite-web,Squarespace/graphite-web,Aloomaio/graphite-web,synedge/graphite-web,piotr1212/graphite-web,evernote/graphite-web,cgvarela/graphite-web,pu239ppy/graphite-web,obfuscurity/graphite-web,AICIDNN/graphite-web,SEJeff/graphite-web,markolson/graphite-web,JeanFred/graphite-web,kkdk5535/graphite-web,krux/graphite-web,DanCech/graphite-web,AICIDNN/graphite-web,graphite-server/graphite-web,graphite-server/graphite-web,graphite-server/graphite-web,pcn/graphite-web,brutasse/graphite-web,markolson/graphite-web,deniszh/graphite-web,Skyscanner/graphite-web,Invoca/graphite-web,brutasse/graphite-web,mleinart/graphite-web,atnak/graphite-web,EinsamHauer/graphite-web-iow,drax68/graphite-web,graphite-project/graphite-web,JeanFred/graphite-web,dbn/graphite-web,mcoolive/graphite-web,synedge/graphite-web,SEJeff/graphite-web,piotr1212/graphite-web,phreakocious/graphite-web,ceph/graphite-web,ZelunZhang/graphite-web,krux/graphite-web,lyft/graphite-web,nkhuyu/graphite-web,blacked/graphite-web,disqus/graphite-web,EinsamHauer/graphite-web-iow,goir/graphite-web,g76r/graphite-web,bruce-lyft/graphite-web,obfuscurity/graphite-web,bbc/graphite-web,graphite-server/graphite-web,penpen/graphite-web,Skyscanner/graphite-web,drax68/graphite-web,edwardmlyte/graphite-web,lfckop/graphite-web,blacked/graphite-web,Skyscanner/graphite-web,evernote/graphite-web,cbowman0/graphite-web,Skyscanner/graphite-web,goir/graphite-web,cosm0s/graphite-web,bpaquet/graphite-web,Krylon360/evernote-graphite-web,bmhatfield/graphite-web,atnak/graphite-web,piotr1212/graphite-web,zBMNForks/graphite-web,drax68/graphite-web,ZelunZhang/graphite-web,cybem/graphite-web-iow,graphite-project/graphite-web,bmhatfield/graphite-web,krux/graphite-web,axibase/graphite-web,disqus/graphite-web,DanCech/graphite-web,zBMNForks/graphite-web,gwaldo/graphite-web,edwardmlyte/graphite-web,zBMNForks/graphite-web,lyft/graphite-web,cybem/graphite-web-iow,Squarespace/graphite-web,deniszh/graphite-web,zBMNForks/graphite-web,dhtech/graphite-web,synedge/graphite-web,penpen/graphite-web,g76r/graphite-web,deniszh/graphite-web,Aloomaio/graphite-web,cybem/graphite-web-iow,bbc/graphite-web,pcn/graphite-web,evernote/graphite-web,MjAbuz/graphite-web,zBMNForks/graphite-web,lyft/graphite-web,pu239ppy/graphite-web,mcoolive/graphite-web,gwaldo/graphite-web,axibase/graphite-web,DanCech/graphite-web,redice/graphite-web,nkhuyu/graphite-web,johnseekins/graphite-web,EinsamHauer/graphite-web-iow,EinsamHauer/graphite-web-iow,cbowman0/graphite-web,EinsamHauer/graphite-web-iow,section-io/graphite-web,phreakocious/graphite-web,bruce-lyft/graphite-web,phreakocious/graphite-web,Squarespace/graphite-web,nkhuyu/graphite-web,esnet/graphite-web,cosm0s/graphite-web,atnak/graphite-web,lyft/graphite-web,obfuscurity/graphite-web,section-io/graphite-web,dbn/graphite-web,Invoca/graphite-web,section-io/graphite-web,piotr1212/graphite-web,krux/graphite-web,cgvarela/graphite-web,disqus/graphite-web,johnseekins/graphite-web,dhtech/graphite-web,mcoolive/graphite-web,cosm0s/graphite-web,MjAbuz/graphite-web,Krylon360/evernote-graphite-web,EinsamHauer/graphite-web-iow,JeanFred/graphite-web,blacked/graphite-web,kkdk5535/graphite-web,penpen/graphite-web,nkhuyu/graphite-web,pu239ppy/graphite-web,johnseekins/graphite-web,cgvarela/graphite-web,cbowman0/graphite-web,lfckop/graphite-web,dbn/graphite-web,bruce-lyft/graphite-web,bpaquet/graphite-web,AICIDNN/graphite-web,nkhuyu/graphite-web,lyft/graphite-web,bmhatfield/graphite-web,pcn/graphite-web,bpaquet/graphite-web,penpen/graphite-web,ZelunZhang/graphite-web,bpaquet/graphite-web,cosm0s/graphite-web,Krylon360/vimeo-graphite-web,johnseekins/graphite-web,cgvarela/graphite-web,ZelunZhang/graphite-web