Add note in README about tagged releases vs master branch.
Jekyll to 2.4.0.
Update highlightjs to 8.3.0.
Update remodal to 0.2.1.
Update normalize-css to 3.0.2.
Set explicit versions in bower.json.
Use new core Firebase auth.
Check-in Gemfile.lock.
Use https for shields.io.
Use https for link to demo site.
Use https over http.
Use ruby 2.1.4 in .travis.yml.
Add caching for Travis; exclude vendor.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	README.md
	_config.yml
	_data/meta.yml