Adds Line Plus Bar Chart Output

Still needs some work:
- Cannot adjust yDomain on either axis, yDomain does not seem to be a method of y1Axis, or y2Axis.
- Have not tried colors
- Have not tried points instead of line
- have not tried rotating the y2Axis label 180 degrees
- Have not tried any disabled series tests
Support for showControls flag

showControls is a method of nv.models.mutiBarChart that shows or hides the control for switching between stacked or grouped bars.  Setting showControls to TRUE shows the control; FALSE hides it.  Passing showControls = FALSE from the renderMultiBarCart function in server.R will hide the controls in the rendered output.
Functional Discrete Bar Chart

A Working Discrete Bar Chart Output.  Available settings include:
- Axis labels (xlab, ylab)
- Margins (mar) not tested thoroughly
- Y Limits (ylim)
- Colors (cols) rgb vectors, r color names, hex codes

At this time, these settings are not supported:
- X Limits: Since these are catagorical, using numeric cutoffs was not working.  For now, just trim your data before putting it into the renderDiscreteBarChart output.
- Multiple series: If you want multiple series use a multibarchart.
Documentation