[Android] Fix the issue of unsupported app.launch.local_path 'http.html'...

....

There is issue if the app.launch.local_path is defined as the specific
'http.html', in the manifest parser, it is differentiating the web url
from local_path via 'http', this fix is resovling this issue by using
'http:' as the differentating keyword.

BUG=https://crosswalk-project.org/jira/browse/XWALK-985