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
Change 'System URL' to 'Direct URL' on System/Process form
Fixes and implementation of roles and user_roles services.
Eliminate obsolete drop of table from migration.
Fixes for permissions lookup and checking.
Merge pull request #55 from reciprocity/feature/change-system-url-to-direct-url

Change System URL to Direct URL
Create barebones prototype
Set revison.content type to TEXT
Migrate events.http_method datatype to enum

Clean up tab spacing to 2 chars
Remove redundant setting of created_at as it is handled by the
framework
Fix typo in migration comment and filename
Merge migrations into 1 file

This prevents unnecessary tweaking of down_revisions when the
merge with development takes time
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
Added context_id to events and revisions
Fix code indentation
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.
Refactored dashboard widgets into controller that can take another controller class for its content; listing widgets on the dashboard now handled by ListView controller