Event block times

[msoucy]

This will probably involve creating blocks during an event to account for fund raising events that are worked in blocks. Should also add a field for comments, for weird edge cases

Blocks link to events which link to the users signed up for them.
Table of blocks, table of user-block links.

Also will involve editing the forms for event creation to add block support.

Originally posted by @msoucy in #2 (comment)

[msoucy]

As of #140 there is preliminary support. Blocks exist, but there's only one block per event.