fix #1362: use default public constructor for ThemeTabFragment and ThemeSearchFragment
Make sure the activity is NOT destroyed when trying to show the notification details screen.
Merge pull request #1363 from wordpress-mobile/issue/1362-themetabfragment-constructor

fix #1362 themetabfragment constructor
Make sure isDestroyed is called on API 17+, and make sure super.onCreate is not called with null parameter in CommentsActivity and NotificationsActivity.
Move isDestroyed() to a separate routine
Merge pull request #1372 from wordpress-mobile/issue/1370-crash-when-opening-notification

Fixing IllegalStateException when opening Notification details from PN
Merge branch 'master' into develop