react-native no longer has a createJSModules

react-native no longer has a createJSModules function, so no @Override required.

[android] Set transparent background.

fix missing assign reject

using RCTExecuteOnMainQueue instead of RCTExecuteOnMainThread…

using RCTExecuteOnMainQueue instead of RCTExecuteOnMainThread, as the function has been removed in react-native 0.42

Remove promise-defer

New Android property "overlay"

Exposing GLCanvas.setZOrderMediaOverlay as React Native prop. Setting
it to true put the new SurfaceView above the previous. Fixes issue #131