English grammar changes

Mainly stuff I missed when creating http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31846&start=0 which is already committed

Reference for this PR is http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31954&start=0