[Android] Enable Chromium command line support

Add the mechanism to support the Chromium command line in xwalk.
1 Read commands from the command line file which locates in assets
in xwalk core.
2 Expose the option to set the Chromium command line in make_apk.py.
3 Add new command "--allow-universal-access-from-file-urls"

BUG=XWALK-1269