Fixes and added new content, migrated to bootstrap 3

- renamed WinterSchoolFeedback to WorkshopFeedback and modified the model so that it has a year property - so it can be reused over the years, and feedback from different years can be compared
- changed from bootstrap 2.3.something to bootstrap 3.0.x, updated forms and carousel accordingly
- changed feedback options, ready for summer workshops '14
- added page that has links to external sites and programs (needs to be beautified, currently wall of text)
- added button to allow course creator to not display a registration button