Merge branch 'tjanson-ghp-relative-paths' into gh-pages
[GHPages] install instruction for python3 users

Additional instruction for python3 users (i.e., pretty much everyone), because `gyp` hates python3 and makes no attempt to find python2.
python3/node-gyp instructions for building node

(Merge remote-tracking branch 'origin/patch-2' into gh-pages)

Conflicts:
	src/templates/get-started.jade