Clean up activity list in manifest.

Remove activities that no longer exist, and sort the remaining ones
alphabetically.
Avoid potential NPE.
Fix exception being thrown on bad connection.

If there's no connection, LoadingFragmentActivity doesn't load the
progress layout. If we don't catch this,
LoadingFragmentActivity.ensureContent() will throw on calling
setContentView().
Merge pull request #167 from maniac103/for-upstream

Fixes for Bugsense reports