Remove unused etc/ReqMgrConfig.py

This configuration file is IMO not used anywhere. Only considered in the
scenario in which ReqMgr gets deployed along with WMAgent deploy script,
I don't think we run this anywhere. @sfoulkes, please review.
ReqMgr - ProcessingString, ProcessingVersion

ProcessingString, ProcessingVersion were missing in the get request response
details. This information is stored only on spec (nor on Oracle or
CouchDB). It may be stored in CouchDB if the request defined this at the
injection time. Added now in the response.
Fixes #4561
Merge pull request #4563 from zdenekmaxa/reqmgr-processing-version-string-in-request-details-2

ReqMgr - ProcessingString, ProcessingVersion
0.9.62

Signed-off-by: Stephen Foulkes <sfoulkes@fnal.gov>
Merge pull request #4560 from zdenekmaxa/reqmgr-remove-unused-config-file

Remove unused etc/ReqMgrConfig.py