Rename BAT spec directory to make room for units

  * Untested code exists to support BATs

Signed-off-by: Aram Price <aprice@pivotallabs.com>
Move code in bat/ into its own namespace and test

  * we relocated the BATs release as part of this for better isolation
  * tests previously under 'bat/spec/' are now at 'bat/spec/system/'
  * classes used to run BATs unit tested at 'bat/spec/bat/*_spec.rb'
  * classes previously under 'bat/spec/helpers/' are not yet tested
  * run the new unit test
  * env_spec.rb is no longer specially run first

Signed-off-by: Aram Price <aprice@pivotallabs.com>
Signed-off-by: Jesse Zhang <jz@pivotallabs.com>