Initial commit of source.

A minimal version of Hermes to get us started. The README is a good place to start. In essence this module exposes a single function, that takes a configuration object and returns a specialized logger function. It also creates a list. Each invocation of the logger appends a notification to this list. Notifications are animated in using CSS, paused for some time after the animation, and then animated out. If the number of notifications goes above the configured maximum, then pause states are cut short or skipped altogether.

Currently Hermes lacks tests and tooling. These will be added, but I'd like some discussion on the code before I go that far. In particular the callback sequence and the state of each notification is a bit hairy, and I'm interested to know if what is going on is clear or not.
I actually tried to do the whole thing in vanilla at first, but there were some issues testing animation events.