Update URLs and other references to downloads to point to downloads.es.net.

(cherry picked from commit 7ec1cbe0c83da85240549ae7f975e2d9c6cff9f8)
Signed-off-by: Bruce A. Mah <bmah@es.net>

Conflicts:
	docs/dev.rst
	docs/index.rst
	docs/news.rst
	docs/obtaining.rst