Update Spyc-library to latest version

Would be a good idea to keep in sync with changes in the Spyc-library used by the REST Server for YAML-parsing and rendering to get performance enhancements etc.

Attached is a patch which updates it to the latest version at https://code.google.com/p/spyc/

I also changed the REST Servers parsing from using YAMLLoad() to instead use YAMLLoadString() since the prior of them can load stuff from the filesystem if handed a filename which might get insecure.

Would be good if someone could verify that it works good after the patch has been applied.