Various Container Execution Enhancements (including GCP Batch support)

[jmchilton]

• Update Galaxy for the latest changes in Pulsar 15.10 - including GCP batch support and some cleanup of TES support.
• Documentation for running jobs via Pulsar on TES and on GCP Batch respectively.
• Some refactoring of Kubernetes runner.

How to test the changes?

(Select all options that apply)

• Instructions for manual testing are as follows:
  1. Instructions included here but also explicit development instructions are included in Pulsar docs @
     • https://pulsar.readthedocs.io/en/latest/containers.html#google-cloud-platform-batch
     • https://pulsar.readthedocs.io/en/latest/containers.html#ga4gh-tes

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.