Add prev/next btns for navigating sections #1849
Minor code cleanup
Merge branch 'master' of github.com:Stanford-Online/class2go into kluo-1849-section-nav-links
Get sections from common_page_data
Merge pull request #1899 from Stanford-Online/kluo-1849-section-nav-links

Add prev/next btns for navigating between single sections #1849