Added context null check to reader service, WelcomeFragmentSignIn now uses the application context when starting the service.
Merge pull request #1902 from wordpress-mobile/issue/1898-npe-reader-service

issue/1898-npe-reader-service
Removed mPagerAdapter, now creating new pager adapter when needed and removing previous adapter before assigning to ViewPager
Check for a valid `comment` before moderating.

Hard to reproduce, but I think this could have happened if the button click event was triggered after `onPause()`.
Create the new comment status from within moderate button's onClick().
Merge pull request #1907 from wordpress-mobile/issue/1900-npe-comment-detail-fragment

Check for a valid `comment` before moderating.
Fixed potential NPEs after calling getPagerAdapter()
Merge pull request #1905 from wordpress-mobile/issue/1899-illegal-state-reader-pager

issue/1899-illegal-state-reader-pager
Merge branch 'release/3.2' into release/3.3