Add spoofax-libs.

The spoofax-libs jar adds the missing SSL_cputime primitive.
Make sure this jar is appears before sdf2imp.jar and strategoxt.jar!
Fix for the new style of builder output.

Spoofax builders now output a (IStrategoString filename, IStrategoAppl ast) tuple
for writing to a file. Sunshine expected the ast to be a String instead of an Appl.

It now also accepts Appl and uses toString to turn it into a string.
Not sure if this breaks anything else though.
Fixed buildfile to actually export spoofax-libs.

Spoofax-libs was only added to the Eclipse build, which meant that it didn't work on the command line.
Now it does.
Merge pull request #1 from VolkerL/spt-port

Add spoofax-libs to work with newer Spoofax