plot type additions

box plots, histograms, and heatmaps
Merge branch 'master' of https://github.com/plotly/MATLAB-api
contour plots
added date type for axis
added matlab versus octave check. boom!
Fix comments
Wrap Plotly's getfile API
rename get_figure -> getplotlyfigure
rename getplotyfigure -> getplotlyfig
interface to plotly's image api
Re-run image generation tests with better filename