only run golint on latest version of go

[cpuguy83]

What does this pull request do?

• Changes travis config to only run golint on latest go version
• Adds 1.11 and 1.12 to to the go version list to test against

Where should the reviewer start?

Does CI pass?
Does golint run on go1.12?

How should this be manually tested?

N/A

Fixes #275
Closes #271

[nathany]

This looks good. Thanks Brian!

It does make me wonder if we need to run gofmt or go vet on anything but the stable release too, but for now it doesn't hurt.

[nathany]

Thanks @cpuguy83. Two questions:

• Have you signed the Google CLA at some point in the past? We're still using that for now. review license and CLA #119
• Is there a related issue with regards to golint not working with older versions of Go? (just to document one of the reasons for this change)

[nathany]

I've removed AppVeyor. This is the appveyor.yml export in case we ever need to bring it back. I will remove the badge shortly.

version: 1.0.{build}
clone_folder: C:\GOPATH\src
environment:
  GOPATH: C:\GOPATH
build_script:
- cmd: >-
    go version

    go get -v -d -t github.com/fsnotify/fsnotify
test_script:
- cmd: go test -v --race -cover ./...

[cpuguy83]

Yes, I've signed the Google CLA, FYI.