Create Up to Date Docs and Deprecate Wiki

We're looking to create some up to date documentation and put it into `docs/` inside the repository. The use of the repo wiki will be deprecated as 'too many cooks spoilt the broth' by editing it a lot with their own ways of doing things.

I want to base the docs off the stuff I started writing for my hubot book (https://github.com/tombell/lhthw I may finish writing it this year, maybe).

I also want to update the README to reflect what `hubot` as a package is, and mainly direct people who wish to hack on the core library rather than 'set up' hubot (directions to the docs will be given).

Some initial points:

Heroku will be officially supported way of deploying hubot, because there are many different ways to 'deploy' hubot to UNIX(-like) operating systems. We can document how to get to a point where you can run `bin/hubot <opts>` on UNIX, but documenting all the ways to handle this like upstart/init scripts etc is outside the scope of the docs for hubot.

Some tasks to get going:

* [x] start initial docs/ directory, copying wiki page
* [x] document creating new hubot
* [x] link to known third party adapters in `docs/adapters.md`

* [x] flesh out CONTRIBUTING.md
* [x] document deploying to heroku
* [x] document deploy to unix (very basic, assume user has installed node, npm, etc, and only cover getting hubot running
* [x] document common things you'd want to do in a script (hear vs respond, random, http, router)
* [x] update src/template/README.md with any info that was in original README.md that would be useful
* [ ] update specific wiki to point at new docs after this been merged