add messages/conversations to mobile

fix flash messages

Fix for #3204 Mobile bookmark not working

update jquery.mentionsInput to latest version
use unminified jQuery.textchange

+ make some tests a little nicer

Updated the Galician (gl) translation.

Fix error admins/weekly_user_stats

Clarify warning shown when single_process_mode used in production

Change root_url to root_path

make the rake task for cleaning up mixed-case tags more verbose

fix some mobile/tablet related stuff

also, (possibly) fix tablet issue #3421, + tests

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This is a fix for public messages, where a malicious pod could spoof a message from someone a user was connected to, as the verified signatures were not checked that the object was also from said sender.  This hole only affected public messages, and the private part of code had the correct checks
THX to s-f-s(Stephan Schulz) for reporting and tracking down this issue, and props to Raven24(florian.staudacher@gmx.at) for helping me test the patch

update-gems [ci skip]

oembed video info box

check for existence of key instead of checking secret twice