CI build steps

[wvanbergen]

• go fmt - see Add go fmt to build #196
• go vet - see Add go vet as build step #195 - requires dropping support for go 1.1
• go lint - see Address some golint suggestions #194 for initial fixes.
• errcheck - requires some fixes to Broker.Open calls
• go test -race - see Fix test raciness #189

@eapache

[eapache]

We will need to drop support for 1.2 as well when we merge #156.

[eapache]

Let's drop 1.1. once we add 1.4 (which should be out December 1st) so we keep the last three stable releases.

[wvanbergen]

• go test -race has been merged.
• PR is open for go vet (Add go vet as build step #195)
• Initial fixes for go lint: Address some golint suggestions #194 Do we want to address everything it suggests?
• errcheck gives us some warning about broker.Open, which can return errors. We'll have to address these if we want to include them in the build process.

[wvanbergen]

We tackled all the golint suggestions we want to fi. Because there's many suggestions that we're not willing to tackle, we should not make it part of CI, but just run it every now and then. Closing this.