Major modification of lang tool
Customers can list users having worked for them. (refs #235)
Fixed warnings when customers is logged in.
Increase width of nordic time-display because it's too small for some dates
Added empty files which require write permission. (closes #277)
Remove files created to test writable temporary directory.
Fixed showing date in invoice. (closes #284)
Merge pull request #287 from ServiusHack/issue/284

Fixed showing date in invoice. (closes #284)
Merge pull request #285 from ServiusHack/issue/277

Added empty files which require write permission. (closes #277)
Merge pull request #286 from ServiusHack/clean_temporary_directory

Remove files created to test writable temporary directory.
Installer checks for PHP version 5.3. (refs #255)
Make updater check for PHP version 5.3. (refs #255)
Removed 5.3.functions.php. (refs #255)
Merge pull request #291 from ServiusHack/php-version-check

PHP version check
Fixed error when user is assigned no groups.
Merge pull request #295 from ServiusHack/user-with-no-groups

Fixed error when user is assigned no groups.
Fixed Italian translation of cellphone.
Merge pull request #298 from ServiusHack/italian_cellphone_translation

Fixed Italian translation of cellphone.
Hide user list when unusable for filtering.

The user list is hidden when it is empty or contains just one user. In
both cases it is of no use to the currently logged in user.
New permission to hide users in same group.

This permission is very helpful for simple users who should not be
allowed to see any other users in their group.