989562 v3

Ok, I modified test_homescreen_launch_app.py and test_homescreen_delete_app.py to add a packaged app for it. This seems to work fine and stable (running it 10 times didn't generate any error)
Some things/issues:
- I need to upload some files to http://mozqa.com/data/webapps/packaged1/ , because on desktop, it's using that url
- I wanted to move install_app to http://mxr.mozilla.org/gaia/source/tests/python/gaia-ui-tests/gaiatest/apps/homescreen/app.py , but I couldn't get that working. For some reason, on the 2nd app install, the confirm button would not be tapped upon.