Partial cherry-pick from add/web-api-links branch

Brings in the minor Wsgi class variable and method renames so that the
mainline will be semi-compatible with the add/web-api-links branch if I
decide to pick up with it again later in the future. This does not pull
in the new url() method or the idea of warmup decorators, which were
ideas that I might be abandoning in favor of a "global" (i.e. static
*and* dynamic endpoints) lookup and URL mapping mechanism.

(cherry picked from commit 77f00b4187b124255c1f274a3e18ae1a81e9f9e3)