Native Debian packaging

I noticed there was some interest in having debian packaging as an option (#163) and I have been eyeing Consul now for the past few weeks. A requirement for me would've been that it exists as a proper Debian package so I decided that I could as well set it up. :)

This is as mentioned in the subject an initial push for now. There are a few things missing still:
* Build folder should be getting a more inspired name
* Version numbers should be picked up from version.go
* The changelog should probably mirror CHANGELOG.md in some fancy way
* Add Makefile target for making both source and binary deb package

There's a minor thing with the branching strategy used for the repository as well, it seems you use neither tags nor a "stable" branch, which makes it hard to actually build only stable releases or so. Something I personally would love to be able to do by following the repository.
I also don't really think my name deserves to go in the changelog footer, so regard that as a temporary thing. I'm more than open to what you guys would like it saying. (Must be both a name and a mail, though)