v2.2.1 release: backports tx v2.1.1 for Istanbul support

[s1na]

See #74 for discussion

[s1na]

So I updated ethereumjs-tx to v2.1.1 on top of the v2.2.0 tag. Also bumped the version and added a changelog entry. It should be ready for publishing if you all think it looks good.

[holgerd77]

For releasing this, I would checkout the respective merge commit and release from there, is this correct (after merging here if course)?

Also tests are failing due to this xvfb thing, can this be corrected?

[holgerd77]

Also: did you have another PR for review today? Wonder if I accidentally deleted some notification.

[s1na]

For releasing this, I would checkout the respective merge commit and release from there, is this correct (after merging here if course)?

Don't merge please, we don't want these changes in master. You could checkout to this branch, build and release directly from there normally.

Also tests are failing due to this xvfb thing, can this be corrected?

I'll make a PR for the xvfb, but LGTM is failing because this branch has merge conflicts with master. That can't be corrected.

Also: did you have another PR for review today? Wonder if I accidentally deleted some notification.

No, no other PR from me.

[holgerd77]

Ok, I have now fetched the branch locally, run the tests locally (which passed) and then published to npm as v2.2.1 and also created the tagged version on that branch. I would now close this PR.