Add spoofax-libs to work with newer Spoofax

I added the spoofax-libs dependency as the SSL_cputime primitive was missing.

Make sure spoofax-libs appears before strategoxt.jar AND sdf2imp.jar in the dependencies.
Otherwise strategoxt.jar will override it.

This made my resolution test cases work with my [spt-branch](https://github.com/VolkerL/spt).