Initial changes in support of a basic permissions set of services.
This includes a new approach to extension modules.
Adopt the new migrate module in migrating GGRC and its extensions
through the db_* commands.
Merge branch 'develop' into feature/roles_and_permissions
Fixes and implementation of roles and user_roles services.
Eliminate obsolete drop of table from migration.
Fixes for permissions lookup and checking.
Extension behave tests can reuse steps from ggrc and can be run using
ggrc.migrate module as a command. For example:
  python -m ggrc.migrate ggrc_basic_permissions/service_specs
However, it is necessary to set the GGRC_SETTINGS_MODULE environment
variable to pickup the required settings modules.
delete renamed module.
Merge branch 'develop' into feature/roles_and_permissions
Role and UserRole CRUD tests, including creation of Adminstrative roles
and checking the service enforcement of those roles.

Also, various enhancements to the ggrc_http steps and supporting
libraries, including the ability to create a factory instance from a
json object specified in a pystring for the step and string literals to
specify a model class to instantiate using a factory.
Merge branch 'develop' into feature/roles_and_permissions
Merge branch 'develop' into feature/roles_and_permissions