separate access domain to diffo_example

[matt-beanland]

We'll want tenants who use diffo to include it as a component, using the extensions.
We should create a diffo_access repo which includes diffo as a component.

[matt-beanland]

Since the Assigner is in the Provider now, we'll want some test cases to test it independently of Diffo.Access

[matt-beanland]

We might call the separated domain something else, like Diffo.Sample, so that it won't conflict with Diffo.Access prior to its removal.

[matt-beanland]

Have created diffo_example which initially uses diffo 0.1.2.

[matt-beanland]

Have cleaned out most of Access, keeping card and shelf to test assignment, and moving it all to test. Have moved ActionHelper from diffo_example back to diffo, it now needs the module and function for the read. It would be good to introspect this from the changeset. Could get the domain and module, but couldn't get the apply call to work for the read.