Add OCI support for container launch
The Open Container Initiative is an industry-led effort to build standard interfaces to the container world. In particular, the OCI defines a runtime specification to define how a container runtime (docker, shifter, singularity, rkt) should deploy a container.
This runtime spec (https://github.com/opencontainers/runtime-spec) has most of what we want to launch containers. We could support most of the container solutions out there by just using this runtime spec as our interface to the container runtime.