First pr merge semver

[jonbodner]

This pull request includes the basic functionality for automatic merging and versioning using semantic versioning.

[bradrydzewski]

is gofmt run on the code? I would expect it to remove the spacing after re

[bradrydzewski]

I do question if auto-tagging is within the scope of LGTM. LGTM focuses on approvals and has a pretty narrow scope. Perform task X when all statuses are passing seems like a separate service, which could be used by people not using LGTM. It also seems like it could include more than just tagging, including deployments, etc. I could also see this as a CI plugin (ie for drone) where you have a plugin that analyzes comments for the merged commit to determine if it should be tagged.

I do think the auto-merge makes sense since, in a restricted environment, you could have maintainers that do not actually have the appropriate access to merge the pull request in which case auto-merge would be very helpful.

[jonbodner]

Heh; quite a few comments. I'll try to get through them tonight or tomorrow.

One quick note: in our internal use of this fork, we've found auto-tagging pretty useful. Sure, it could be in a second bot, but it's nice to have merge and version happen at the same time.

Also, the code was go fmt'd, but individual commits might not have been. I'll fix this on the branch along with the other comments.

[jonbodner]

I've addressed several of the issues pointed out. I still need to write tests to cover the changes, but I wanted to get some feedback first. If you're going to be at GopherCon, we can meet up and talk some more about which changes you want to incorporate.