Install with Pkg.clone(pwd()) instead of ln -s

After seeing the message [here](https://groups.google.com/forum/?fromgroups=#!topic/julia-users/Kt2KtQm2O1Q) I wanted to see if installing the package differently would help. Since a PR triggers Travis, this was the easiest way to check my assumption :P
Fetch unshallow
Merge pull request #24 from tlycken/patch-1

Install with Pkg.clone(pwd()) instead of ln -s, adds unshallow to fix cloning problem