Move v0.6.7 examples to subdirectory
Set up example redirects

/example/foo/ redirects to /example/v1.0.0/foo/ if it
exists, otherwise /example/v0.6.7/foo.

As a special case, /examples/ redirects to /example/v1.0.0/.

/example/ and /examples/v1.0.0/ have always been 404s.
Link to v0.6.7 API docs and examples from v0.6.7 pages
Point to v1.0.0 examples on v0.6.7
Merge pull request #368 from mapbox/example-redirects

Set up example redirects