fix(API): Content-Length header not set for 416 status

The latest HTTP 1.1 RFC states that the Content-Length header MUST NOT be
set for 1xx and 204. It is also normally not set for 304. 416 is not
mentioned, so we should set Content-Length for it.
Merge pull request #284 from kgriffs/master

doc(hooks): Correct docstrings wrt bound methods
doc(hooks): Note new resource param in docstrings for decorators
Merge pull request #283 from kgriffs/bug

fix(API): Content-Length header not set for 416 status
feat(hooks): Run global "after" hooks even when an exception is raised

This patch causes Falcon to execute the list of global "after" hooks
after an exception is raised. Before this change, exceptions would
circumvent the hooks, so there was no opportunity to install, for
example, a custom serializer that could also act on errors.

Note that per-resource and per-responder "after" hooks will continue to
be circumvented after applying this patch; it was deemed to hacky
to make those work. If an elegant solution can be found, and there is
a good use case for doing it, we can revisit this issue.

Closes #250
Merge pull request #285 from kgriffs/issues/250

feat(hooks): Run global "after" hooks even when an exception is raised
doc(hooks): Better document gotchya around resource param
perf(API): When seaching responders, unpack each route in one step
Merge pull request #286 from kgriffs/chore

chore: Take care of some nits