Clean up BarChart Functionality

[austingulati]

While building a dashboard, I found myself needing the BarChart view. I cleaned it up and added a few features. Notable points:

1. BarCharts now support multiple series
2. Demo now has one BarChart

I haven't worked with d3 in the past so some of my code may not be doing things the d3 way. One concern I have is using calculateX and calculateY that call the x() and y() functions set up by d3. I did this so that it could be extended in the future, for example adding a stacked bar chart would be easy with some simple changes to calculateX and calculateY.

Let me know when you get a chance to take a look at this. I can make changes as necessary.

[jondot]

Hey Austin, sounds really really great, thanks!
I've caught a bit of a cold but I hope to check it as soon as possible

[jondot]

@austingulati hey dude. well apparently after I finished with the cold I had to deal with a break up. so it took some time, sorry.
I just checked out your work and it's really awesome. pulling, thanks!