Title: #220: Fix setting up [application] domains without inherit_from
To test, just define an application domain as the only domain in the config
file and do not use the inherit_from attribute.
A more detailed description is in the commit description.
To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/220/head:pr220
git checkout pr220