Add US phone number formatter

[svemir]

Added US phone formatter with a separate protractor test and a karma test, and a tweaked the gulp file to create a separate build file masks.us.js that only has the global masks and the new us phone mask.

There is probably a cleaner way to do the whole BR vs US thing, but for now I tried to do it in a way that leaves the existing stuff alone. Further splitting up can be done separately.

NOTE that I use element by id in protractor tests because by model and by bind seem to create warnings even in existing tests.

[coveralls]

Coverage increased (+7.05%) to 25.84% when pulling 603bcac on Symplicity:us-phones into ea3f23f on assisrafael:master.

[assisrafael]

Nice!
I will take a merge it ASAP.