Make database warning translatable
Improve Private Feed setting description.

This is how they do it in core :wink:
Fix activity widget text
Fix header text of select elements on the list table

Was #172
Use _x() instead of __() appropriately

This will give translators better context
Provide .pot file

This file should be used by translators to update their translations.

For example, using POEdit:
1. Fire up POEdit
2. Open your language's current .po file
3. Click **Catalog** > **Update from POT file**
4. Translate away and save.
Update .po file based on new .pot
Update Polish language to use new placeholders
Merge branch 'master' into issue-173

Conflicts:
	connectors/installer.php
	connectors/posts.php
	connectors/widgets.php
	includes/list-table.php
	includes/settings.php
Merge pull request #176 from x-team/issue-173

Issue 173: Translations force placeholders order