updated entity and entity subscription requirements. Started changing tests to account for the new entity interface
added migrations to change subentity_type to subentity_kind. Performed two migrations so that the user has the ability to write a data migration
updated all tests to work with entity kinds rather than entity types
bumped version
updated docs
updated release notes
updated docs to let users know they are responsible for writing the data migration between entity types and entity kinds
Merge pull request #15 from wesleykendall/develop

Updated group entity filtering to use EntityKinds instead of ContentTypes
Merge pull request #16 from ambitioninc/develop

Updated entity emailer to use entity kinds rather than entity types