Description of problem:
When creating an SNMP alert notification the OID is empty, but is a required field.  As we have the OID populated in the server plugin, we should be able to input the OID in the server plugin as a default value for the case that the user does not care to customize their alerts (ie, so they don't have to look up the RHQ OID for each new alert they create).

Version-Release number of selected component (if applicable):
JON 2.4.1