ability to set container ulimit

[iangkent]

It would be nice to be able to set container ulimit via maestro-ng deployment description file (yaml).

• http://docker-py.readthedocs.org/en/latest/hostconfig/#hostconfig-helper
• https://docs.docker.com/engine/reference/commandline/run/#set-ulimits-in-container-ulimit
• https://docs.docker.com/compose/compose-file/#ulimits