Reverse get_indexable() so new stuff gets indexed first

This helps a ton during development since you can do:

    ./manage.py esreindex --percent=10

and get something useful that'll show up on the dashboard.

This will also help production since it'll populate the index with the
most recent stuff first.
[bug 966426] Add has_email filter to analyzer search
[bug 966426] Add test for has_email filter