Added support for more fields. Explained github fallbacks.
Added support for more fields. Explained github fallbacks.

In reference to https://github.com/nanoc/nanoc.ws/issues/25#issuecomment-25605384
jaspervdj/static-site-generator-comparison,barryclark/static-site-generator-comparison,digideskio/static-site-generator-comparison,unic/staticsitegenerators-list