Adding basic 'Event Manager' functionality

This is work from day 1 of the Mozilla Science Lab Global Summer Sprint with @npch and @gperu

We created routes and templates for managing events (i.e. bootcamps) via DB queries (rather than editing the roster.sql file)

https://etherpad.mozilla.org/sciencelab-2014summersprint-admin-tool has some more detail on what was done.

Please note that 5e334733edb7353eb690002e6e8f4b9a4e1436c also adds a new column to the `Event` table in roster.sql, presumably making it incompatible with the copy in the main (private) repo. This will be also flagged on the main repo by raising an issue.

If there is another, preferred, way of modifying the DB structore, please let me know.
Let's make this URL a bit more semantic, e.g. `/events/<id>/update`. Another option is to combine this with `/events/<id>/edit` route and have an `if` statement for the `GET` and `POST` requests.