Most of the way towards a cal implementation for #11

Using [iCalendar](https://github.com/tritech/node-icalendar) package (from [Midas](https://github.com/Innovation-Toolkit/midas) fame) to generate ics files server side. The major outstanding issue here is that solr is not returning the results I'd expect. I search for id="some_id" and it returns many results which don't contain the id. I think I am just missing something (hopefully) obvious.

I set it up as a /v0/cal/record_id endpoint since that made the most sense to me for this particular issue. But it may make more sense to make it a query parameter based endpoint if there is a desire to build calendars with multiple events in the future.