Fix project file count in Import tab, add summed file size

[Jason Gerard DeRose]

Currently broken, needs to be fixed, and we also need a solution that doesn't have performance issues.

Paste from https://plus.google.com/u/0/114471118004229223857/posts/Lv7WrrxVssJ

"""
I'm working on a fix for one of the +Dmedia bugs that +Joshua Brown brought up during our "User Testing On Air" hangout :P

Long ago +James Raymond had this working for the file count, and then at some point I apparently broke it by removing the CouchDB view it used.

But the solution James came up with had serious performance problems if the needed views weren't up-to-date because it had to hit a view in each project database.

Now I'm reworking this to store the file count and summed size in the project "directory" docs in dmedia-0, so only one view is hit (project/title), and in only one database (dmedia-0). Although now it's possible for the count and size to be slightly out-of-date, this first screen will always load very quickly, which I'd say is more important.

Oh, and dmedia-service pre-initializes the project/title view, so it will typically be up-to-date by the time the user runs dmedia-gtk. And even if the view is out-of-date, we're using an asynchronous request, so the UI wont block while waiting for the result.
"""