add constructor for Builder

this makes it easier to track required dependencies as they change

(todo: actually, like, use it for required dependencies)
introduce Queue object

this is an intermediate step towards pushing configuration up.

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>
inject docker client into Builder

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>
split build construction out of worker

(todo: inject runner into worker)

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>
provide runner to workers, use it for all builds

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>
Merge pull request #125 from vito/injectable-builder

Injectable builder (and friends)