Add status to issues

* Add a dedicated table to store the different status an issue can have
* Add a foreign key on the issue table providing the status of the issue
Update the edit issue form to include the issue status
Update the internal API regarding issues to account for their status
Update the edit issue controller to account for the issue's status
Display the issue status when editing an issue
Only show opened issues in the issues tab
Allow the edit_issue to edit only a part of an issue
Create a simple form to edit only the status of an issue
Add macro to represent a form field as list (<li> tags)
Enable editing the status of an issue from the status's view