Add PostgreSQL for storing schedules

[ahoskins]

I like the way the RIT db works.

I'm guessing the workflow is:

1. press "save" button while on schedule view
2. db stores the current schedule, busy times, and preferences
3. we give the user a url they can access this at (we could even let them create their own hash, that would be fun)
4. when that hash is requested, node queries the db with the hash which gives an associated schedule, busy times, and preferences
5. deliver this is a special view to the client (a view not showing the busy times and preferences sliders basically)
6. there's a button on this page prompting the normal site to be loaded

[rosshamish]

Cool, I like this. There's already preliminary support for this in classtime too, "more like this" schedules get stored in the db and return a hash id

[rosshamish]

^ my first comment is a misunderstanding of what this feature would be. I think I understand now.

this could possibly couple well with rosshamish/classtime#99 (cache responses to common requests). In addition to saving individual schedules, whole search results (lists of schedules) could be shared by sharing the sched-gen query string. And maybe winston could fire a request to classtime to "forcibly cache" a sched-gen request on save.