Remove python buildpack config

[dsabeti]

Are you submitting this PR against the develop branch?

Yes, however, this change does depend on first merging #697.

What is this change about?

The python_buildpack_name field is never used by CATs, so this PR removes all references to it. In fact, despite having this configuration parameter, the Config interface does not expose a GetPythonBuildpackName() function as it does with most other buildpacks, so we know programatically that this field is never used.

(The Python asset is used only in the detect test suite, where no buildpack name is specified on purpose -- the test exists to validate that a Python app is successfully detected by CF even when the user does not explicitly specify a buildpack.)

Please provide contextual information.

N/A

What version of cf-deployment have you run this cf-acceptance-test change against?

N/A

Please check all that apply for this PR:

• introduces a new test --- Are you sure everyone should be running this test?
• changes an existing test
• requires an update to a CATs integration-config

Did you update the README as appropriate for this change?

• YES
• N/A

If you are introducing a new acceptance test, what is your rationale for including it CATs rather than your own acceptance test suite?

N/A

How many more (or fewer) seconds of runtime will this change introduce to CATs?

N/A

What is the level of urgency for publishing this change?

• Urgent - unblocks current or future work
• Slightly Less than Urgent

Tag your pair, your PM, and/or team!

@aramprice

[ctlong]

@dsabeti @aramprice I think this branch needs a rebase

[ctlong]

@dsabeti @aramprice I think merging #700 created merge conflicts for this PR, and unfortunately another rebase is required.