Update justified nav CSS for proper selectors

BS3 commit 4357ed7
Use padding instead of #push with box-sizing: border-box

BS3 commit 0959a78
include info on the Bootstrap CDN

BS3 commit 7cceaa6
updated to latest BS3

BS3 commits e1d947f, 9d9fd5e, 7cceaa6, 747e108, 7d41a38