Cleaning up a bunch of things:

1) Moving "about" into its own controller. This makes way more sense,
even though it's all just serving static content. I can deal with magic
pattern-matching jiggery-pokery in the next commits. Routes are still
not perfect.

2) Cleaned up the main Servlet, moving a couple things (Gravatar) into
config places lesewhere.

3) Cleaned up layouts by renaming a copy of _calavera.jade to
default.jade so Scalate can grab it automatically.