Test coverage + small project infrastructure changes

### Hello!

I ran into diesel a few days ago while I was looking for a name for a personal project, and ended up finding this amazing tool!

But then I found painful to discover the dependencies and hack in it, and when I finally managed to do it and went to run the tests.... I discovered I had to have MongoDB and Redis running for the protocol tests to run.

## so I did some work in the project infrastructure...

I've been doing a lot of work lately related to processing markdown, I
even have a project finds python code blocks inside of markdown files
and run them as "acceptance" tests.

I also feel that restructuredtext is somehow less attractive or perharps more complex than markdown.

Markdown the default format in github, this pull request is being
writen in markdown, and I like it and I wanted to propose that diesel
adopted markdown as the format for documentation, but I'll talk more
about it in more detail in the end of this pull request.

decided to [revamp the readme file](https://github.com/gabrielfalcao/diesel/blob/master/README.md) a little, as well as the [Makefile](https://github.com/gabrielfalcao/diesel/blob/master/Makefile).

I also put all the dependencies inside of the [requirements.txt](https://github.com/gabrielfalcao/diesel/blob/master/requirements.txt), and changed the setup.py file so it reads its dependencies for it.

## and started to add test coverage...

I am the author of [lettuce](http://github.com/gabrielfalcao/lettuce), [HTTPretty](http://github.com/gabrielfalcao/HTTPretty), [Sure](http://github.com/gabrielfalcao/sure) and some other python test libraries, software robustness is something that fascinates me, and building scallable software is my passion, so I am stufying diesel's code just for fun, and in order to learn all of it, I am committed to add 100% of unit test coverage as well as working on a better test infrastructure.

Diesel is great, but I believe its codebase could look a little more modularized and tested.

Please let me know if it interest you guys, I'd love to join the project.
![2013-06-16 05_59_51](https://f.cloud.github.com/assets/54914/659178/84a9011e-d66b-11e2-89a0-6481b301d5e6.gif)