[Android] Embedding API version 4.0

New APIs in 4.0:
XWalkUIClient.onCreateWindowRequested
XWalkUIClient.onIconAvailable
XWalkUIClient.onReceivedIcon
XWalkView.getRemoteDebuggingUrl
XWalkResourceClient.onReceivedSslError
Merge pull request #2551 from wang16/embedding_api

[Android] Embedding API version 4.0