Parallelize deb_all and mock_all in jenkins

Currently our jenkins deb_all and mock_all jobs build targets serially. This
commit changes this to build targets in parallel, by posting separate jobs to
jenkins for each target, allowing jenkins to queue. This does introduce n*cows
+ n*mocks increase in data upload, but in a high-bandwidth, large storage world
this is still a major optimization.

Signed-off-by: Moses Mendoza <moses@puppetlabs.com>