Pass around a Search ID

To be able to go from:
- User searched for foo
- User viewed N Minis
- User left site for a Mini

Todo List:
- [ ] Generate a unique ID on search
- [ ] Pass ID between pages
- [ ] Pass ID to /Minis/Details
- [ ] Pass ID to /Minis/Redirect
- [ ] Add ID to ViewedMini
- [ ] Add ID to MiniRedirect
- [ ] Make a funnel