help buttons and text for matrix types
size nodes by betweenness
remove zeros from geodesic plot (because they don't carry significance, every vertex has a zero path with itself)
add note in display options for 'More' tab
warning popup for chrome
merge

Merge branch 'master' of https://github.com/statnet/ergm-shiny

Conflicts:
	statnetWeb/ui.R
	statnetWeb/www/style.css