Error for non-existent attribute value while adding matcher.
Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1299789
Description of problem:
Currently If we are trying to add matcher for 'non existing attribute' in Smart Class Parameter/Smart Variables it raises as error 'Match <attribute_name> = <value> does not match an existing <attribute_name> ' and this is only applicable when attributes are FQDN/HostGroup. It seems this doesn't work / not added for other attributes such as OS, domain etc.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Create a matcher for non existing attribute(other than FQDN, HostGroup) for smart class parameter / variable other.
2. Attempt to submit.
No Error raised for Attribute not existing in satellite.
Error should be raised for non existence of attribute and for all the attributes.