CMake support, license candidate, better test structure, a readme file.

I've been looking at the library and I quite like it.
I'm disappointed it's not licensed yet, meaning legally it cannot be used by anyone.
It would be really nice to bring it a step further, even though the library is really minimalist.

- I added support for CMake, that way it can be included easily as a git submodule by any major project.
- I added a README.md file for github with helpful directives.
- I cleanup file header comments that are meaningless.
- I created a CREDITS.txt file that list authors and maintainers on the project.
- I added a LICENSE-candidate.txt file containing a copy of the MIT license.

Please have a look (https://github.com/nitrix/talloc).
I'd love if this is accepted, otherwise, I may start a fork with your permission.

Cheers,
nitrix