further fixes of py3 issues

complaints by pylint are mainly related to
- remove object from base list in class definitions
- unnecessary else/elif after return/raise

Change-Id: I13d15449149cc8bba0562338d0c9c42e97163bdf
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/21325
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/server.py

@@ -40,7 +40,7 @@ except ImportError:
     import daemon.pidfile as pidlockfile
 
 
-class Server(object):
+class Server:
     # list allowed section prefixes
     # if mapped dict does not exist -> section need a 'class' option
     # otherwise a 'type' option is evaluatet and the class from the mapping dict used