Brush/VIT/Multi-plot/namespace refactoring....

[jimmoffitt]

• Updated "div id" namespace: tweet --> tweet_from_map, tweets --> tweets_vit, timeline --> timeseries
• Added support for second line plot.
• Now displaying VITs in tweet timeline widget.
• Updated brushing, now defaults to integral hours. Need to stop Twitter embedded widget when moving brush.
• Referenced data set is event_viewer.json (removed version number)
• Added "play" button and have associated "animate" code (which needs works!)
• Need to add animation transition/delay
• Made associated 'namespace' updates to style.css and prac8.html.