Install mpi-operator

[lwilson]

Is your feature request related to a problem? Please describe.
We need to be able to run MPI jobs on the Kubernetes cluster

Describe the solution you'd like
mpi-operator from KubeFlow should do the trick: https://github.com/kubeflow/mpi-operator

Describe alternatives you've considered
We could build our own operator, but that seems unnecessary

Additional context
I think we should install the MPI operator separate from KubeFlow, as some users may want to run MPI jobs independently of using KubeFlow's other features.

[j0hnL]

we should include a working example along with this installation. Running a simple tensorflow w/ horovod or mpi 'hello world' would be fitting

[lwilson]

We currently have an MPIJob example which uses apiVersion kubeflow.org/v1alpha1 and runs the Tensorflow Benchmark: https://github.com/dellhpc/omnia/blob/devel/examples/k8s-TensorFlow-resnet50-multinode-MPIOperator.yaml.

Should we add another example that uses apiVersion kubeflow.org/v1alpha2 (e.g., https://github.com/kubeflow/mpi-operator/blob/v0.2.2/examples/v1alpha2/tensorflow-benchmarks.yaml)?

[j0hnL]

Remove the old v1alpha1 example and move forward with master branch of mpi-operator

[lwilson]

@j0hnL should we rely on master or stick with a tagged release?

[lwilson]

I changed this to use master instead of v0.2.2. See #48 (comment)