feature(client): Add a horizontal bar chart, use it for the browser breakdown.
chore(client): Give the horizontal-bar chart more left-margin to accommodate long browser names
chore(client): Change all pie charts to horizontal bar charts.
chore(server): Remove the unneeded placeholder text on the demographics page
refactor(client): horizontal-graph size calculation cleanup.

* Calculate the height of the graph based on the number of items.
* Calculate the width of the graph based on the size of the container.
Merge branch 'no-more-pie'