Use upstream codecov instead of our own fork

[nmaludy]

We've been seeing repeated build failures for codecov issues: https://travis-ci.org/github/StackStorm/st2/jobs/710376520#L27406

The fix is to upgrade to codecov-python >= 2.1 per https://community.codecov.io/t/http-400-while-uploading-to-s3-with-python-codecov-from-travis/1428/6

However, we are maintaining our own fork of codecov-python and those changes haven't been merged into our fork.

Couple things here:

• It looks like we're maintaining our own fork so that we can get better error outputs: codecov/codecov-python@master...StackStorm:better_error_output
• I've submitted a PR upstream to include these changes so we don't have to maintain our own fork: Include output in error message codecov/codecov-python#288
• Once the PR above is merged we can merge this PR

Until we get the changes merged upstream, i've also submitted a PR against our own codecov-python fork to pull in the upstream changes so our tests can pass again without these errors: StackStorm/codecov-python#2

DECISION POINTS / OPTIONS

1. If we don't mind having the "better error messages" shown in case of codecov failure, we can merge this PR and just use upstream

• At some point in the future our "better error messages" PR will be merged and we'll take advantage of that automatically

2. We can let this PR sit until the upstream changes are merged and instead merge PR Sync with upstream master into our special branch codecov-python#2 so we can stop getting errors in our builds.

[punkrokk]

Just restarted the failed job

[arm4b]

Thanks for digging in deeper trying to fix the Codecov issues in st2 CI 👍