chore(uses): Rename uses -> use

Rename `uses` method to `use` on both `$translate` and `$translateProvider`

BREAKING CHANGE: API of both $translate and $translateProvider is changed. To migrate you
have to change all `uses` method call to `use`

Before:

$translate.uses('en');
$translateProvider.uses('en');

After:

$translate.use('en');
$translateProvider.use('en');
Merge pull request #323 from DWand/uses-to-use

chore(uses): Rename uses -> use