Add slave recipe to create Jenkins slaves

Rewrote integration tests to use Vagrant instead of test-kitchen because test-kitchen does not support multi-node setups.

Signed-off-by: Adam Stegman <astegman@pivotallabs.com>
Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>
Signed-off-by: Matthew Boedicker <mboedicker@pivotallabs.com>