Appengine

After the disaster that was #3, it's clear that we most likely need a server-side component - trying to run file scans on a phone is hella slow. So, our goals are:

1. Provide a Dropbox key, we start scanning for ROMs
1. We stream this down in JSON-per-line format, one ROM per line
1. In the Android app, we display sync status 
1. We display the list of synced ROMs in a listbox once we're done