Added cmake support to cpputest

This adds cmake support to cpputest. Think the linux support is, at least close to, equivalent to that of automake.

One big difference from this and the automake support, is that this actually compiles gmock and gtest if you want gmock/gtest support. The reason for doing this is that it was easier to implement, and we don't have to make any assumptions as to where the libraries are, as we control that.