(Bug 51577) SMW\PropertyDisparityDetector (lift some scope creep in ParserData)  

This change helps to eliminate some scope creep in ParserData
which does too may things at once (has currently a CRAP of 2140).

SMW\PropertyDisparityDetector
Comparison is done synchronously but job generation has been moved
into a backgound dispatcher to shield against timeouts when
getAllPropertySubjects() is executed.

Code coverage: 100%
CRAP: 15

SMW\PropertySubjectsUpdateDispatcherJob
Generates UpdateJobs in order to rebuild property-subject parity

Code coverage: 100%
CRAP: 15

Change-Id: I81a4b206e1548e48475c6318ec4728b3cd8cb924