[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
(cherry picked from commit a7d6ef18fb02a10cc8095161887cc7e9c1ac7e8b)