Allow PUT and POST for acceptance info API
Add a custom trivalued logic schema type.

This corrects and issue where if the has_accepted value was None,
it would change the value to True.
Sync role acceptance with publishing. Addresses #138

This corrects and issue where a revision would not sync up previously
accepted values into the newly created content.
Populate publishing tables for revision cases to work from.
Add the users found in the archive database.
Add backwards compat line for licensors inside declare_roles.

This is necessary for when we don't fetch the latest updated content
from storage before sending the content to the user.
Add another revision tests. This one includes more than one user.

This is further verification of the roles sync with publishing
when creating a revision.
Add license acceptance sync for revision creation. Addresses #138

This will sync the license acceptance with publishing when a revision
is created.
Ensure users who accept their roles after rejecting have edit privileges

Close #163
Merge pull request #164 from Connexions/issue-138

Fix issue #138
Merge pull request #166 from Connexions/allow-put-acceptance-info

Allow PUT and POST for acceptance info API
Add pre-publication validations.

This adds a new property to the models called ``is_publishable``,
which also gets set out in the response as ``isPublishable``.
This boolean value can be used to both stop a publication on the
backend and/or disable publication on the frontend.
Insert the is_publishable property into a binder's tree results.
Adjust the is_publishable property on binders and add are_contained_publishable.

This gives the cascading behavior a new property and allows the is_publishable
value put into a binder tree to be isolated to that specific model.