Relax the RegEx restrictions to allow the new ICAAN TLDs.
fix-#733: index_cls is ignored when deciding to set _cls as index prefix
Merge pull request #738 from DavidBord/fix-733

fix-#733: index_cls is ignored when deciding to set _cls as index prefix
Update for add the change that closes issue #733
Update .travis.yml for allow failures in pypy3
Allow atomic update for the entire `DictField`
Merge remote-tracking branch 'upstream/master'
Adding changelog entry.
Merge pull request #742 from bocribbz/dictfield-atomic-update

Allow atomic update for the entire `DictField`
Update changelog.rst
Fix conflict for merge PR #726
Merge branch 'jshirley-master'
Makes 'db' argument to connection optional.
Merge pull request #737 from wcdolphin/master

Make 'db' argument to connection optional
Update changelog.rst
fix-#746: Stop ensure_indexes running on a secondaries unless connection is through mongos
fix-#397: Allow specifying the '_cls' as a field for indexes
Merge pull request #719 from DavidBord/fix-397

fix-#397: Allow specifying the '_cls' as a field for indexes
Change with PR #719 and close mongoengine/Issue #397
Fix merge of PR #747