Add a setup script for the jenkins slave.

Summary:
This will be used to create an AMI that the slave machines will use
when we start them up.

Test Plan:
Fingers crossed.  Will try installing and creating an AMI and using it
with the jenkins ec2 plugin.

Reviewers: chris

Differential Revision: http://phabricator.khanacademy.org/D9874
Add a setup script for the jenkins slave.

Summary:
This will be used to create an AMI that the slave machines will use
when we start them up.

Test Plan:
Fingers crossed.  Will try installing and creating an AMI and using it
with the jenkins ec2 plugin.

Reviewers: chris

Reviewed By: chris

Differential Revision: http://phabricator.khanacademy.org/D9874