Organisational units, series, events and groups

Pretty massive PR including:

Organisational units:
 * CRUD
 * Getting / Adding / Deleting series from an organisational unit
 * Getting the organisational unit tree

Series:
 * CRUD
 * Adding / Deleting events to/from series

Events:
 * CRUD


It's pretty rought, but I'll go do some self-review (which hopefully gets in before @nicolaasmatthijs gets on the plane)
Yeah, we're already generating over 8k log statements so the Travis output buffer overflows. We should look into zipping up the logs and shipping them to S3.