Adding unsigned int support to mock

According to issue 21:

https://github.com/cpputest/cpputest/issues/21

I'm adding support to unsigned integers on the mock framework. Sadly i committed some changes to autotools macros and to the configure, it is not a good practice to keep these things on the repository (all projects that uses autotools that i worked only keep these on the release tarballs, not on the repository).

I will have more attention on the future with this.