Update story "Create RedisLabs user-provided service"

[pstahl-pivotal]

The behavior of the RedisLabs site doesn't match the instructions. In particular, in Step 2, Redis now provides a password by default. Also, make sure students choose the FREE 30MB plan; in one of the sign-up steps, evil RedisLabs defaults to a paid plan, and the student MUST change it back to FREE. Finally, the host and port are indeed on the endpoint row, but not all students will know how to separate host and port (they're concatenated together on the RedisLabs page).