Remove '--output /dev/null' from specs per commit c580206bafcac2030e78098b8c542137ae3c17c7
Add spring support, with command implementation identical to zeus

Spring uses a command prefix together with automatically-spawned
background processes that close when you leave your terminal session,
negating the need for a separate, manually controlled server process.
Abstract out executable prefix, handle zeus/spring + binstubs
Merge pull request #152 from shanesveller/spring_support

Spring support