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_demo/cryo.py

@@ -125,7 +125,7 @@ class Cryostat(CryoBase):
     commands = dict(
         stop=Command(
             "Stop ramping the setpoint\n\nby setting the current setpoint as new target",
-            [],
+            None,
             None),
     )
 

secop_demo/modules.py

@@ -314,6 +314,6 @@ class DatatypesTest(Readable):
 
 class ArrayTest(Readable):
     parameters = {
-        "x": Parameter('value', datatype=ArrayOf(FloatRange(), 100000, 100000),
+        "x": Parameter('value', datatype=ArrayOf(FloatRange(), 0, 100000),
                         default = 100000 * [0]),
     }