release 1.58.1
release 1.58.1

247f464 Update README for 1.58.1  ( zxcpoiu 2017-06-14 19:11:33 +0800)
f764455 android,ios: update WebRTC 58 build  ( Saúl Ibarra Corretgé 2017-06-13 13:18:33 -0500)
5a3291b [Android] Fix EGL context leak  ( Lyubo Marinov 2017-06-13 13:57:06 -0500)
7e54c12 js: fix `_mergeMediaConstraints()`  ( zxcpoiu 2017-05-23 13:37:15 +0800)
e362793 js: move default pc constraints to const  ( zxcpoiu 2017-05-23 13:14:45 +0800)

zxcpoiu/react-native-webrtc,zxcpoiu/react-native-webrtc,zxcpoiu/react-native-webrtc,zxcpoiu/react-native-webrtc,zxcpoiu/react-native-webrtc,zxcpoiu/react-native-webrtc