Normalize url in trigger parameters
Normalize url in trigger parameters

* Leading or trailing slashes in the url coming from the rule
  would cause the API to reject webhook requests.
* Normailzing the url to not include trailing or leading / means
  that the match is / agnostic and StackStorm does not end tripping
  over some silly /.

nzlosh/st2,peak6/st2,lakshmi-kannan/st2,Plexxi/st2,tonybaloney/st2,tonybaloney/st2,punalpatel/st2,Plexxi/st2,pixelrebel/st2,nzlosh/st2,StackStorm/st2,tonybaloney/st2,lakshmi-kannan/st2,peak6/st2,dennybaa/st2,nzlosh/st2,punalpatel/st2,nzlosh/st2,dennybaa/st2,StackStorm/st2,StackStorm/st2,emedvedev/st2,dennybaa/st2,lakshmi-kannan/st2,emedvedev/st2,pixelrebel/st2,StackStorm/st2,emedvedev/st2,Plexxi/st2,peak6/st2,Plexxi/st2,pixelrebel/st2,punalpatel/st2