Allow arbitrary images to provision Jenkins slave
Jenkins execution nodes can be tagged, so a Jenkins job runs on a server
ready for that.
Instead to create a unique 'jack of all trades' Jenkins images, we want to
be able to create more specialized images, for different needs or set of
For example, we need to provision a slave with Rust capability.
Test Plan: Check the state is no op as far as Jenkins slaves for CD are concerned.
Reviewed By: dereckson
Differential Revision: http://devcentral.nasqueron.org/D1728