Lib/config: Create a list of pathes only for confdir

Under some condition (no general config file) it's possible that the
piddir and logdir as well are lists of pathes which creates some errors
during the server start

This problems occurs at least in NICOS test suite where no general
config file is defined.

Change-Id: I94c5db927923834c1546dbc34e2490b07b0bf111
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/34952
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Jens Krueger <jens.krueger@tum.de>

frappy/lib/__init__.py

@@ -98,7 +98,10 @@ class GeneralConfig:
                     missing_keys.append(key)
             else:
                 if not isinstance(env, Path):
+                    if key == 'confdir':
                         env = [Path(v) for v in env.split(':')]
+                    else:
+                        env = Path(env)
                 cfg[key] = env
         if missing_keys:
             if configfile: