Makefile

[mjtrangoni]

Hi @brandonweeks,

I did a bunch of small changes here, which are the things I enjoy using/seeing when building an exporter. This also cover #10 needs.

• Implement a Makefile using promu as build tool.
• Use more Prometheus Libraries.
• Update some vendoring adding govendor support.
• Add an initial README.md file.
• Add travis.yml configuration, but you should enable travis for you repository.
• Add -version flag and also gives a hypothetical 0.0.1 version.
• Implement Makefile docker target for building.

What I would like to do in other PRs is,

• Fix some gometalinter issues, filter some noisy tests, and make this target default.
• Implement promu crossbuild.

I hope you enjoy the changes, and I am open for code-review, too.

[cristicalin]

Great work!

Some suggestions:

• it would be nice be able to run make build and get the binary on a system without the go build environment, this means you can use a golang:1.8-onbuild image and trigger the build in there
• as the build is done outside, you may want to modify the Dockerfile and base it on alpine:latest instead as it should only be a runtime image