Removing code

Hello, 

This is an audacious pull request. The idea is to propose a change that may extend to other LuaDist packages: Remove original source code from the package.

In this example I am removing the source code of `busted`, instead I am adding a routine to download the original source code. And tried to keep full compatibility with the original functioning of luadist.

This process may facilitate the maintenance of packets, avoiding complicated processes merge therefore makes it clearer what is the responsibility of the code for this project versus the code of the original design.

Finally, this is just a proposal, perhaps I have not fully analyzed the effects of this change, suggestions and comments are welcome.