Fix bug in HybiParser.

Thanks @koush for finding this.
Null check
Use gradle build system.
Use readFully method.
Validate Handshake Response

Make sure that the server response includes a Sec-WebSocket-Accept
header and that it's what it should be.
Merge branch 'master' of https://github.com/codebutler/android-websockets

Conflicts:
	.gitignore
	android-websockets.iml
	build.gradle
	src/main/java/com/codebutler/android_websockets/WebSocketClient.java