Add :cljs-build-fn to the lein-project schema (#619)
Add :cljs-build-fn to the lein-project schema (#619)

Since 0.5.0 the build-fn can be specified from the config, but the schema
validation wasn't aware of it, so actually doing so would result in an error.
This adds it to the schema so the option is recognized.
verma/lein-figwheel,bhauman/lein-figwheel,bhauman/lein-figwheel,verma/lein-figwheel,bhauman/lein-figwheel