Small performance improvement on imap_open

Use the OP_HALFOPEN flag to reduce server load. We don't need to open a mailbox, so just don't try
I've also make the check clearer for the opened connection (I know, 2 PR in one, it's bad…)
Move template code from lib/Data to template file

Fix #1729
Change license header to small version and replace echo with p()

Fix #1729
[tx-robot] updated from transifex
Merge pull request #1723 from Glandos/patch-1

Small performance improvement on imap_open
Correctly check whether previewImageLink is set

Fix #1729
Do not use echo for html in template/list.php
Remove more HTML echo
Add missing callCheck() to ajax/settings.php in Activity App

As per https://github.com/owncloud/apps/issues/1705#issuecomment-39579951
remove unmaintained/moved files_tree app
remove unmaintained/moved xmpp app
[tx-robot] updated from transifex
Merge pull request #1749 from owncloud/remove-unmaintained-files-tree

remove unmaintained/moved files_tree app
Merge pull request #1730 from owncloud/issue/1729

Move template code from lib/Data to template file
[tx-robot] updated from transifex
[tx-robot] updated from transifex
[tx-robot] updated from transifex
[tx-robot] updated from transifex
Merge pull request #1742 from owncloud/activitiy/add-call-check

Add missing callCheck() to ajax/settings.php in Activity App
[tx-robot] updated from transifex