Aula 2013-03-22 - Uri hierarchy factories using interfaces.

Support for URI creation using factories.
Uri parse using polymorphism in constructor which is not a good idea as some tests show.
All tests pass but Mailto and Geo types are not fully supported.
Merge branch 'master' of https://github.com/lfalcao-isel/POO-LI21D-LI23D-1213v