Removal of workaround flags

[Matthias Boehm]

just a little heads-up: I intend to the remove the recently added 
workaround flags DISABLE_SPARSE and DISABLE_CACHING because any 
underlying issues should be directly addressed. Furthermore, I was not 
able the reproduce the issues reported in SYSTEMML-1140, probably due to 
improvements that have been introduced since it was created. So, if you 
feel these flags are still required, let's discuss it here.

Regards,
Matthias