LDAP: clear the cache not only when TTL changes, but with every settings...

Checkstyle fixes 

Just one CSRF token per session

Checkstyle: many fixes

Files: change wording 'From url' to 'From link'

Backport of de1b95c

Before, the CSRF token expired every hour. We had a script in place
which should refresh the token but this don't worked in every case.
(Laptop sleeping etc.)

With this commit, the token will only get once created for every
session so that the "Token expired" warning shouldn't appear.

Use $.each() instead of for(var...) in oc.dialogs. Fixes accessing undefined vars in IE8.

Send the requesttoken as form value

checking quota in webdav

Tests for p and print_unescaped added

check for database error in userExists

I'm not sure if IE9 is also affected, so I changed it to "older IE versions" - IE 10 should work fine.