Flocker config resource limits floc 963

Fixes FLOC-963
Also we only want to have one internal representation in the parsed config on an `Application` for a memory limit and given that we then marshal those loaded configs back in to YAML to send to other nodes and inspect containers via the Docker API, which always returns memory limit in bytes, it makes more sense to me to stick with that unit. I don't even really like the idea of accepting strings with a number and unit identifier in the Flocker YAML tbh, but I'd be happy to go with that if we internally converted everything to bytes.