Add migration for new options
Improve consistency tokens
Refactor tagging logic to fix bugs post refactor.

refs #227
First pass plugin API entrypoints
Cosmetic changes and refactoring of visuals
Merge branch 'master' into extract
Kill nonsense migrations
Add _fieldnames to subrecord models.

Use this statically declared shortcut to get fieldnames_to_serialise if it's defined.

refs openhealthcare/elcid#226
Frist commit - developer docs.