change locally served URL to /en/latest to match deployed docs
use relative links for hero
relative paths for gallery
streamline gallery creation and use CDN resources for gallery plots
small fixes to Makefile
remove commented code
updated fabfile

deploy: backup and rsync, and set latest symlink
update: backup and rsync, do not set latest symlink
Merge pull request #1609 from bokeh/task/1608_docsbuild

Docs build/deploy improvements