Fix logic error with constructing Context- and View- querysets

Subclasses were supplying the archived keyword argument which would
prevent the `if not kwargs` check from ever succeeding. It has been
fixed to ensure there is either a session key or an authenticated user
associated with the request.
Fix legacy `write` method, update to `render`

This is due to a change in broth/restlib2@bc5227e9
Implement ConceptFieldsResource

This is a convenience endpoint for getting a concept's related fields.
Move SAFE_METHODS to base module
Add travis-ci config