Fix/gofmt and read cert cleanup

[smoser]

• Reduce code in extractPubkey by using readCertificateFromFile.

  Less software in the world.

• Add a 'gofmt' target for make and call it as a trust dep and from c-i

  My editor automatically runs 'gofmt'. So its annoying to open a file,
  make a change and see a bunch of whitespace unrelated changes in place.
  Ok, maybe I should fix my editor, but really 'gofmt' code is the norm.

  The change here is to run gofmt and fail the build if it makes changes.
  That way those changes don't get checked in and don't pass c-i if it
  hasn't run.

• Run gofmt and commit changes.

  These are whitespace only changes, the result of running gofmt.

[hallyn]

I don't think the go fmt in the github action is useful. But it won't hurt anything, most likely.

I find automatic mandatory linting by a constantly changing set of rules to be a bad idea. But I admit I'm extra bad about this, so maybe the side effects are better than the disease.

[smoser]

I don't think the go fmt in the github action is useful. But it won't hurt anything, most likely.

i think you didn't realize that the target fails (and c-i will thus fail) if gofmt makes changes.
that way, we dont check in changes that haven't been go-fmt'd.