Create the AdminAction class and its search function
Add the add_new_request_branch method to the internal API

This method allows register a new branch request in the AdminActions
table.
Update the logs to support package.branch.request send upon new branch request
Expose the search_actions method in the internal APi

This method behaves similarly to the search_logs method by allowing the
user to find the actions requiring admin intervention matching a set of
criterias
Add a dedicated form to request a new branch for a package
Add the admin_actions endpoint

This endpoint exposes the actions requiring admin intervention in a
similar manner as the admin_logs endpoint
In the front page of the admin section add the link to admin_actions
Add the list_actions template required for the admin_actions endpoint
Add the request_branch template used to request a new branch for a package
Add the package_request_branch endpoint allowing to request for a new branch on a package
Forward to the package's detail page if there are branches that are 'missing'

These branches could thus be requested (allows us to display or not the
`request new branch` button)
Add the `Request new branch` button if it makes sense and make it a pop-up as the others
Link the user and the package to their respective pages
Make the action table a little prettier
Give a little space on both sides of the cells
Hide the request new branch button if the user is not logged in
Bump the requirement of sqlalchemy 0.8+

Looks like the addition of the AdminActions table and its double mapping
to the Collection table leads to the requirement for a newer version of
SQLAlchemy
Remove debug code
Validate that the user requesting a new branch is a packager
Add unit-tests for pkgdb2.ui.package_request_branch