Add Array.prototype.random for shiz and gigs
Use proper accept header for client requests

Swapped "request.is" for "request.accepted."

We should be inspecting the "Accept" header to specify html/json, rather than the
"Content-Type" header.

Sample request:

$curl -H accept:application/json 127.0.0.1:3000
Merge pull request #1 from matt-holden/master

it automerges, which is above my lower threshold for concern.