add snippet completion support for directives on query
add snippet completion support for directives on query

Reviewed By: kassens

Differential Revision: D21643728

fbshipit-source-id: 3cb541a2b23fba4eb4bf7d4b2a7a7798b06b428c

kassens/relay,kassens/relay,wincent/relay,atxwebs/relay,atxwebs/relay,facebook/relay,wincent/relay,wincent/relay,wincent/relay,xuorig/relay,kassens/relay,xuorig/relay,facebook/relay,voideanvalue/relay,yungsters/relay,kassens/relay,kassens/relay,voideanvalue/relay,xuorig/relay,atxwebs/relay,josephsavona/relay,xuorig/relay,atxwebs/relay,facebook/relay,facebook/relay,josephsavona/relay,kassens/relay,xuorig/relay,voideanvalue/relay,wincent/relay,yungsters/relay,facebook/relay,voideanvalue/relay,voideanvalue/relay,xuorig/relay,voideanvalue/relay,facebook/relay,yungsters/relay,josephsavona/relay,wincent/relay