Use default langugage in CliConfig
Use default langugage in CliConfig

Summary:
Fix: https://github.com/facebook/relay/issues/3802

ith CLI options typescript is the default language - should be flow (the default in TypegenLanguage now).

Reviewed By: kassens

Differential Revision: D34619078

fbshipit-source-id: 05720397474350b7739e06b0a2c6b4fb5a03f5bf

kassens/relay,voideanvalue/relay,xuorig/relay,wincent/relay,facebook/relay,xuorig/relay,xuorig/relay,facebook/relay,kassens/relay,kassens/relay,wincent/relay,wincent/relay,voideanvalue/relay,facebook/relay,facebook/relay,facebook/relay,kassens/relay,xuorig/relay,voideanvalue/relay,wincent/relay,wincent/relay,kassens/relay,xuorig/relay,xuorig/relay,facebook/relay,voideanvalue/relay,voideanvalue/relay,kassens/relay,wincent/relay,voideanvalue/relay