Code cleaning

I removed the Firefox-addon-sdk, hogan.js and closurelibrary from the third_part directory. Now they are not tracked in github (they are not part of the project, they are requirements now!).

I made a "build.sh" script that installs everything automatically
It doesn't include the code. Rather, it's a reference to a repository url and commit id using a few metadata files (`.gitmodules`, `.git/config`). Perhaps you're confusing it with a [git-subtree](http://blogs.atlassian.com/2013/05/alternatives-to-git-submodule-git-subtree/)?