Show a border around unfocused inline editors.

Now that we no longer show the "OK" and "Cancel" buttons for single-line inline
editors, it can be confusing when one edits the summary but no draft banner
appears because the editor hasn't been saved.

This change adds a red shadow on the outside of any text inputs which have lost
focus, to indicate that something's not saved.

Testing done: Checked out the new border.

Fixes bug 3242.

Reviewed at https://reviews.reviewboard.org/r/5631/
Allow using extension management commands in rb-site manage.

rb-site manage was loading the site configuration but not initializing
all of Review Board. This meant that any custom management commands
couldn't be used. We now initialize Review Board so that all extensions
are also loaded.