Migrated exceptions module from mls.fabfile.
Migrated environments module from mls.fabfile.
Migrated utils module from mls.fabfile.
Migrated rackspace module from mls.fabfile.
Added module to manage frontend server services.

- Currently supports restart for nginx, varnish and ha-proxy on debian
  systems.
Not mls related.
Migrated database module from mls.fabfile.