Fix bug added when we changed AppDescription.maxCores to an Option

The Scala compiler warned about this -- we were comparing an Option
against an integer now.
Enable shuffle consolidation by default.

Bump this to being enabled for 0.9.0.
Merge pull request #378 from pwendell/consolidate_on

Enable shuffle consolidation by default.

Bump this to being enabled for 0.9.0.
Merge pull request #375 from mateiz/option-fix

Fix bug added when we changed AppDescription.maxCores to an Option

The Scala compiler warned about this -- we were comparing an Option against an integer now.