Fix gce_demo for loadbalancing and Python 3
Fix gce_demo for loadbalancing and Python 3

The firewall for loadbalancing needs to have "target tags" set instead
of "source tags" and the print statement fails on Python 3.

Closes #776

Signed-off-by: Eric Johnson <6a226512a569016c3805352ca112daa827043ceb@google.com>

ZuluPro/libcloud,niteoweb/libcloud,samuelchong/libcloud,apache/libcloud,ZuluPro/libcloud,pquentin/libcloud,DimensionDataCBUSydney/libcloud,illfelder/libcloud,samuelchong/libcloud,Scalr/libcloud,t-tran/libcloud,DimensionDataCBUSydney/libcloud,mgogoulos/libcloud,SecurityCompass/libcloud,erjohnso/libcloud,iPlantCollaborativeOpenSource/libcloud,erjohnso/libcloud,vongazman/libcloud,erjohnso/libcloud,watermelo/libcloud,pquentin/libcloud,wuyuewen/libcloud,StackPointCloud/libcloud,samuelchong/libcloud,NexusIS/libcloud,watermelo/libcloud,techhat/libcloud,mathspace/libcloud,NexusIS/libcloud,vongazman/libcloud,apache/libcloud,mgogoulos/libcloud,pquentin/libcloud,andrewsomething/libcloud,Kami/libcloud,mathspace/libcloud,supertom/libcloud,lochiiconnectivity/libcloud,Kami/libcloud,techhat/libcloud,illfelder/libcloud,watermelo/libcloud,t-tran/libcloud,ZuluPro/libcloud,wuyuewen/libcloud,Kami/libcloud,Scalr/libcloud,ByteInternet/libcloud,wrigri/libcloud,Scalr/libcloud,andrewsomething/libcloud,lochiiconnectivity/libcloud,ByteInternet/libcloud,wuyuewen/libcloud,illfelder/libcloud,niteoweb/libcloud,mistio/libcloud,wrigri/libcloud,t-tran/libcloud,mistio/libcloud,wrigri/libcloud,supertom/libcloud,apache/libcloud,SecurityCompass/libcloud,supertom/libcloud,lochiiconnectivity/libcloud,NexusIS/libcloud,niteoweb/libcloud,ByteInternet/libcloud,mistio/libcloud,mgogoulos/libcloud,StackPointCloud/libcloud,techhat/libcloud,iPlantCollaborativeOpenSource/libcloud,mathspace/libcloud,SecurityCompass/libcloud,iPlantCollaborativeOpenSource/libcloud,DimensionDataCBUSydney/libcloud,StackPointCloud/libcloud,vongazman/libcloud,andrewsomething/libcloud