Update to ReqMgr Oracle/CouchDB consistency tools

-description in the README file
-couchdb consistency checker and correction started
-couchdb dumper
-frequent running of Oracle, CouchDB database consistency (e.g. the same
number of requests in both databases) checker made easiler
Merge pull request #4497 from zdenekmaxa/reqmgr2-oracle-couch-consistency-checker

Update to ReqMgr Oracle/CouchDB consistency tools
First round of ReqMgr CouchDB values fixes.

First round of ticket 4388
https://github.com/dmwm/WMCore/issues/4388#issuecomment-15390453

Removed from CouchDB:
"ReqMgrGroupID"
"ReqMgrRequestID"
"ReqMgrRequestorID"
"ReqMgrRequestBasePriority"
"WorkflowSpec"

Unittests and reqmgr.py checks that these request parametrs never appear in
CouchDB on newly created requests.

"RequestWorkflow" is left on requests, contains URL of the spec file, though
it's redundant, parameter is however forbidden on injection and is set by
ReqMgr. Spec manipulation depends on presence of this argument. Too many
changes would be required to get rid of it. reqmgr_request:worklow would be
ported if necessary to Couch or removed completely in ReqMgr2.
Merge pull request #4499 from zdenekmaxa/reqmgr-fixing-database-consistency-issue-4388-1

First round of ReqMgr CouchDB values fixes.
Second round of ReqMgr CouchDB values fixes.

RequestSizeEvents - in majority of couch requests not defined, no references
    in the code (probably was at some point), should be removed from all Couch
    requests ; deprecated, injection fails will fail now if specified
RequestEventSize - deprecated, injection fails will fail now if specified,
    should be removed from all old Couch requests
SizePerEvent - must exist, parameter is mandatory, from Oracle is taken from
    reqmgr_request:REQUEST_EVENT_SIZE (mess that the above probably existed
    when someone was introducing SizePerEvent)
RequestSizeFiles - made mandatory, handled properly so that values are stored
    in Couch, on old requests values should be loaded from
    reqmgr_request:REQUEST_SIZE_FILES
RequestNumEvents - made mandatory, handled properly so that values are stored
    in Couch, on old requests values should be loaded from
    reqmgr_request:REQUEST_NUM_EVENTS
PrepID - made optional, properly stored in Couch, on old requests values
    should be loaded from reqmgr_request:PREP_ID

All unittests updated. reqmgr.py now contains checks for the above.
Database Oracle -> CouchDB migration/consistency scripts should implement the
above when migrating values.
Merge pull request #4500 from zdenekmaxa/reqmgr-fixing-database-consistency-issue-4388-2

Second round of ReqMgr CouchDB values fixes.