Made RNGLContext.java thread-safe (fixes rare exception with simultaneous shader compilation)

Made RNGLContext.java thread-safe (fixes rare exception when a shader is used in multiple surfaces at the same time)

+ can potentionally explain/fix other witnessed crashes

android: mask out only RGB channels of background colour

Fixed import in GLCanvas.m

upd_build_tools

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