Avatar cleanup

 - PM code now using avatar service.
 - Enhance gravatars module with preferences options.
 - Change max size defaults in avatars module to 128px to more easily use 128x128 icon libraries.
Merge remote-tracking branch 'upstream/master'
PM avatar service conversion
Namespace issue in Logger and Dtype
Avatar service implementation
Changes as discussed in PR #101
Merge pull request #103 from geekwright/master

Cleanup related avatar service implementation