Bug 913324 - Select biggest icon that fits on the screen

When launching an app, we display one of the icon defined in its
manifest. If the application defines several ones, then we need to
select the biggest one that fits into the screen.
Merge pull request #12847 from lissyx/bug913324

Bug 913324 - Select biggest icon that fits on the screen r=vingetun
Bug 927458 - Remove test_homescreen_launch_here_maps.py as it is unlikely to be returned to the build, r=zac
Merge pull request #12896 from bobsilverberg/remove_HERE_maps_test

Bug 927458 - Remove test_homescreen_launch_here_maps.py as it is unlikely to be returned to the build, r=zac
Bug 927475 - update marionette client
Merge pull request #12841 from lightsofapollo/break-the-world

update marionette client