removed libraries for offline work
changed introductino links
added number (Lesson 0) next to unit introduction
expander text now reflects its status
working on styling navbar
styled header better
fixed header html, added arrows
header links are now the entire div, not a link, and the navbar title is static
removed extraneous variable
Merge branch 'curriculum' of https://github.com/Thinkful/pysplash into curriculum