Merge pull request #27 from ysb33r/master

Added project.jrubyexec support
Mark the version up to 2.2.0 for this milestone's development
Reduce duplicate declarations of the spock dependency
fixup! Mark the version up to 2.2.0 for this milestone's development
Parent gemInstallDir under $project.buildDir

Fixes #28
Added more notes about testing
Fixed test related to project.jrubyexec
Fixed ordering issues between 'test' and 'integrationTest' tasks