FSE-207: runsvdir is still running during chef-container testing

Managing processes in chef-init was a PITA. To address this I created a new class called ChefInit::Process that used the sys-proctable gem to give me a more reliable way to find and interact with processes. All process management is now handled directly through that. The actual code that was being used didn't really change - it's just been shifted around. 

In addition, I cleaned up the rspec tests and fixed a few minor issues with the gemspec file and the Dockerfile. 
I think something like this might be easier to read:

```
max_wait = 10
wait = 0
until @supervisor.running? || max_wait == wait do
  sleep 2
  wait += 1
end