Auto-approver: pathless template with unique name

One of the time-wasters with import queue review is template uploads without directory paths. For example, a known template might be "plugin/plugin.pot" after which the user uploads "plugin.pot".

When the auto-approver sees a template upload with no directory path, it could do a base filename match. When exactly one current template matches (in this case, "plugin.pot"), then that's the right template and the upload can be approved.

I can't come up with any legitimate scenarios where this would disappoint. It saves time in the case where maintainers sometimes upload tarballs, and sometimes individual templates without browsing to the template's UI first. This may actually increase, relative to total manual approvals, as more people use bzr imports for day-to-day translations management but do the occasional manual upload.