Egan dev

adds rider, can add a rider to a carpool (for developer/demonstration purposes)
the way to add riders to a carpool needs to be polished and I will continue working on that, but I wanted to submit this pull request to show you what I've been working on.

One major issue is the fact that I can't load in the Carpool model from rider.js, so right now the schema and methods for rider are in the carpool.js file as an easy work around. If you find out why it doesn't work please tell me so it can conform to our normal schema per file convention.

How I plan on improving adding riders to carpools:
* When a carpool is created, add all players associated with the creator
* allow users to confirm riders for rides
* allow users to say that they need a ride
* make sure the same person can't be added twice
* make sure you can't add a rider when the carpool is full.
* allow person offering ride to add multiple players at once.

These are changes I will be working on this week. I will push those commits to this branch, and if it hasn't been merged I'll comment on the pull request explaining what I added.

Thanks