Add a generic is_authenticated method is use it in the decorators
Check if the user has commit or watch* on devel and forward the info to the templates
Disable some of the options on the left menu if the user already has commit or watch* ACLs
Add a title to the button to explain a little more what they allow
Grey-out the options when they are disabled
Rework the logic checking what ACLs the authenticated user has

According to the ACLs the user has, options will be enabled or
disabled in the UI.

Fixes https://github.com/fedora-infra/pkgdb2/issues/23
Retrieves the ACLs a package can have from the database

This avoid having the list hardcoded
Disable the 'Request ACLs' button if the user already has all the ACLs one can have