Initial commit of basechurch engine

Output of
be rails-api plugin new basechurch -T --mountable \
                                   --dummy-path=spec/test_app
Set up engine to run specs
Move model specs to engine
Move serializer specs to engine
Move validator specs to engine
Move controller specs to engine
Replace old Rails app with engine

Move the engine code to the root directory as the main contents of this
repository.
Add default rake task to run specs
Namespace all models and controllers
Add seed data
Clean up gemspec
Update README to support basechurch engine
Merge pull request #10 from openmcac/engine

Convert basechurch-api into a Rails engine