add a new lib to aid testing, dictdiffer
Refactor tests and add new test capabilities

1. Refactor fixtures so that you can ask a factory for an application,
its form, or its form information (and same for journal).

2. Add a helper to diff dicts more easily.

3. Rename a method in dao which was overriding the keys() method of the
built-in dict and breaking a test.

4. Add new journal xwalk test.
remove unnecessary print stmt
refactor Journal form contexts; remove common JournalContext ancestor and use PrivateContext directly in all journal contexts
add a check in all concrete form renderers that field groups specified for numbering and error checking are actually defined
Merge branch 'feature/formcontext' of github.com:DOAJ/doaj into feature/formcontext