Remove InvalidParameterValue exception

The InvalidParameterValue exception does not define a meaningful
msg_fmt.  It is currently _("%(err)s"), which is the equivalent of
nothing and does not help with translation.

Replace InvalidParameterValue with Invalid exceptions.

Change-Id: If8b064e446cbc97e380127f360f262be9e8877a1
Closes-Bug: #1538398

watcher/common/exception.py

@@ -133,12 +133,6 @@ class InvalidGoal(Invalid):
     msg_fmt = _("Goal %(goal)s is not defined in Watcher configuration file")
 
 
-# Cannot be templated as the error syntax varies.
-# msg needs to be constructed when raised.
-class InvalidParameterValue(Invalid):
-    msg_fmt = _("%(err)s")
-
-
 class InvalidUUID(Invalid):
     msg_fmt = _("Expected a uuid but received %(uuid)s")