[Android] Support http://w3c.github.io/manifest/ for packaging tool

Support "start_url", "xwalk_launch_screen" and "xwalk_permissions" field in manifest.
The legacy field "launch_path", "app.launch.local_path", "launch_screen" and "permissions"
are still supported, but will print a warning message.
Merge pull request #2134 from jinbang/tool_support_w3c_manifest

[Android] Support http://w3c.github.io/manifest/ for packaging tool