[Android] Use Uri for the web socket url for remote debugging

Class URL doesn't accept ws protocol in case openConnection is
called in future without handler.

Use Uri class instead, this is a minor change to the API
not released to customers yet. Roll up the API version to 4.1.

BUG=https://crosswalk-project.org/jira/browse/XWALK-2893
Merge pull request #2583 from wang16/embedding_api

[Android] Use Uri for the web socket url for remote debugging