Make API apps search follow docs for dev/device parameters (bug 1060062)

This fixes incoherencies between the API and the docs regarding `dev` and `device` parameters. They are super confusing, but I need them to be coherent for https://bugzilla.mozilla.org/show_bug.cgi?id=1060062

This patch make the API match what fireplace is sending and what the docs are specifying. The rocketfuel and feed API were already doing the right thing.
This also makes me sad my tablet work never landed.