A few minor change

Move RESTTesting.txt to RESTTesting.md
Add a menu for all the entities.
The twig templates are calling some non-existant properties on Content entites. This
should fix them.
Merge branch 'cleanups' into crudcleaning

* cleanups:
  The twig templates are calling some non-existant properties on Content entites. This should fix them.
  A few minor change

Conflicts:
	src/LOCKSSOMatic/CRUDBundle/Resources/views/Content/index.html.twig
	src/LOCKSSOMatic/CRUDBundle/Resources/views/Content/show.html.twig