CRS objects are seriously not recommended.

I've removed them from the spec and only refer to them via refs
to the original geosjon.org format spec.

Under interoperability considerations, I push all responsibility
for use of non-default CRS onto servers and reiterate that servers
must not under any circumstances give out lat,lng data. Doing so
creates a world of hurt for developers.
Bump some text from section 6 up to section 3.
Anthropomorphize data formats no more.
Change [GeoJSON] to [GJ2008].
Merge pull request #40 from geojson/seriously-not-recommended

CRS objects are seriously not recommended.