Pause install script for Mac users to turn on Mongo

After Mongo is installed, it is not turned on for mac users
but running `rake cms:update_templates` requires Mongo to be started,
so the script usually crashes. Pausing the script to allow users to
start Mongo should solve this problem.

I thought it would be best to simply pause it and allow users to
turn on Mongo themselves. Another option would be to just
start Mongo automatically.

@natehardison Take a look! :)