add citypop ggplot graphs

3 graphs
1) citypop grouped by top 5 cities
Revert "add citypop ggplot graphs"

This reverts commit 4300e85319c828045c0a88ab0e456a2deed52624.
adding intro

Aarti[aj177] intro
Merge branch 'gh-pages' of https://github.com/aj177/edav into aj177-gh-pages
naming convention (#73)