Bumping version to 5.3.0.20150611

Bumping internal version to 5.3.0.20150605

Merge pull request wordpress-mobile#3713 from wordpress-mobile/issue/…

…adds-missing-remove-observer

NotificationDetailsViewController: Adds missing removeObserver call

Bumping internal verison

Merge pull request wordpress-mobile#3570 from wordpress-mobile/issue/…

…3569-tracks-crash

Fixes crash when logging in with self-hosted site

Bumping to version 4.9.1

Updating release notes for 4.9.