* Add trusted application functionality
This lets users apply for trusted status, given certain minimum
requirements. Moderators can then review the applications, giving
a recommendation, and administrators can accept or reject them.
If an application is accepted or rejected, the user receives an
e-mail about it.
Markdown images are not rendered in applications to prevent browsers
from sending automatic requests to untrusted webservers.
Users who have had their application rejected cannot re-apply for a set
amount of days.
* minor fixes
