Add status endpoint

Return package version and software name. Clients can poll this to
see if the backend is up and running.

Signed-off-by: Christoph Kassen <c.kassen@telekom.de>
add tests for status endpoint

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
Merge pull request #45 from TelekomCloud/feature/status_endpoint

improvement: add status endpoint