big rework to comply to current spec

- adapt to release(v2018-11-07)
- remove duplicate errors.py
- adapt tests

Change-Id: I383bb571f9808c72b37c12fbe55042011c4c0084
Reviewed-on: https://forge.frm2.tum.de/review/19397
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>

secop/features.py

@@ -112,9 +112,9 @@ class HAS_Timeout(Feature):
 class HAS_Pause(Feature):
     # just a proposal, can't agree on it....
     accessibles = {
-        'pause': Command('pauses movement', arguments=[], result=None),
+        'pause': Command('pauses movement', argument=None, result=None),
         'go':    Command('continues movement or start a new one if target was change since the last pause',
-                         arguments=[], result=None),
+                         argument=None, result=None),
     }