Merge pull request #3 from elasticsales/latest_mongoengine

Latest mongoengine + a fix for ANDed queries on the same fields.
Update AUTHORS
Update AUTHORS
no more support for py2.5 in travis since maintaining it isn't a priority
use unittest backport for py3 test features
adding unittest2 for py3 as well
more changes to see if builds work on travis
unittest2 for py3w
moar pymongo versions
use the elasticsales pymongo driver
Dummy commit.