Revert "hide add Youtube video link"

This reverts commit 0b25dbba507b2d2638177c47e4744154dffd43d0.
basic Backbone model for Page
hardcoded grid view of pages
highlights on mini pages
remove hardcoding of source file with temp solution
render pages through DocumentView
DocumentView.setPageViews creates new array of PageViews w/each sort (overwrites highlights)
sort highlighted pageviews by page & number of annotations
basic filtering of pages w/annotations&questions
add num threads to page stats
basic column chart
all page numbers in x axis labels
hover over page numbers for page preview
highlights in enlarged page preview
arbitrary gradients for labels, 'questions' to 'replies requested'
styles, js cleanup, pg num hover quickfix
navigation links
some js rearranging
added tip
propagate changes in Gruntfile.js to compile analytics