- Remove presentation information from Service model (order, icon)
- To access the list of services filled with both presentation and api
  data use Service.catalog(). The method fills a dict with service
  identifiers and service metadata through the following steps
    - Initialize a service dict using
      astakos.im.presentation.service_defaults
    - Extend (merge and overwrite) it with the correspoding entry in
      astakos.im.presentation.SERVICES if exists.
    - Merge once again if user has set service metadata in
      ASTAKOS_SERVICE_META setting. This way user can change only the
      desired service parameters.

- An example of ASTAKOS_SERVICE_META containing keys which

    ASTAKOS_SERVICE_META = {
        'myservice': {
            'name': 'service_identifier',
            'url': 'https://service.url/service/ui/',
            'verbose_name': 'My service name',
            'order': 1,

            # cloudbar specific parameters
            'cloudbar': {
                'show': True,
                'title': 'My service name in cloudbar'
                # defaults to verbose_name
            },

            # dashboard specific parameters
            'dashboard': {
                'show': True,
                # we use different ordering in dashboard
                'order': 100,
                'description': 'My service description'
            }
        }
    }

- Updated dashboard to use Service.catalog() instead of hardcoded
  html.
- Updated service-* commands to keep up with model changes