better clusterIP filtering logic, add default services

[memory]

• pull the inline python one-liner out into a separate script so
  that we can:

• apply better logic around filtering out service.spec.clusterIP:
  if the value is "None" that's a headless service
  and not preserving the value will result in the creation of
  a NON-headless service, which is likely to be extremely wrong.

• set explicit_start=True in the call to pyyaml.safe_dump() so
  that backup files can be safely concatenated together

• add serviceaccount to the list of default resources

• update the README with the current defaults

• add EXTRA_ env vars for the resource lists so that they can be appended to as well as overwritten

[memory]

n.b. I spent a little bit of time trying to figure out if there was a straightforward way of doing a conditional key deletion in JQ's query language and did not make much progress, but I won't claim that it's not possible.

[pieterlange]

Excellent, good catch on the headless services! This script was written before those existed..

Could you remove backendconfigs from the default resources though? Its not portable.

[memory]

Fair enough about the backendconfig, and this reminded me that I wanted to also make it a little easier to simply append to the resource list rather than overwrite it.

[memory]

@pieterlange comments addressed, look good?

[pieterlange]

Sorry for the delay. Looks good, but i'm gonna try to catch this logic in jq instead so we don't deviate too much from the "this is just a shellscript project" concept. Will merge after i've done that.

[memory]

Ping? :)

[memory]

Poke -- did you have any luck trying to port this logic into jq?