Brazilian portuguese translation and fixes 2

Update and fixes, thanks
added messageview_autofit_width and translation
Merge remote-tracking branch 'origin/pr/307'
Merge remote-tracking branch 'origin/pr/306'
Move Japanese translation of the changelog into the correct directory
Remove override annotation so we can use the latest SDK to compile
Always include currently opened message in the message list

This should fix various bugs where moving to the next/previous message
didn't work.
Bumped manifest to 4.502
Remove abstract Activity from manifest
Update targetSdkVersion to 17
Increase minSdkVersion to 8 because we're using SearchView in FolderList
Correctly initialize mSingleAccountMode

This fixes a NullPointerException when trying to open account settings
from the Unified Inbox (when there's only one account).
Merge remote-tracking branch 'upstream/master'