bug 1536903: improve bulk processing performance
bug 1536903: improve bulk processing performance

This fixes the query so that it pulls the list of crash ids rather than
all the information, then create a bunch of instances, and then take
the crash ids from those instances. That's a lot of extra work.

mozilla/socorro,mozilla/socorro,lonnen/socorro,mozilla/socorro,lonnen/socorro,mozilla/socorro,lonnen/socorro,mozilla/socorro,lonnen/socorro,mozilla/socorro