Some clarification.

Some small changes to clarify things.

- The *foofah* example had some errors and its not used during the whole example.
- The gemspec didn't use the *foofah* example but was placed in order to be part of it.
- Endorsement of ruby 1.9.3 instead of 1.8.7
- Well lots of credit to @dhh but to clarify better lets avoid awkward possibilities -so people would actually understand that its ok to fill in their own names ;)

Then I noticed down below that the examples was based on very old releases for spree, should it not encourage per default to build extensions for the current master branch?