Move JS to bottom of page

Create layout properties for the angular app and body controller
and use the same pattern as for head tags to let templates fill in
the body content while the base template inlines scripts at the
bottom.
Neurotic normalization of template boilerplate

Because I'm like that. :sparkles: :alien: :sparkles:
Merge pull request #1171 from hypothesis/jstobottom

Move JS to bottom of page