Bug 1076706 - [Smart Screen][Home] Implement card listing and launching function

Please review only the commit of Bug 1076706, because the base (bug 1076702) has not landed yet

https://bugzilla.mozilla.org/show_bug.cgi?id=1076706
nit: I understand the setting is copied from phone's, but could we blacklist a type when we actually have to? So maybe `input` and `search` shouldn't be added at first.