add colobar to hist2d function
added colorbar to imshow function
Fixed indention and naming as suggested in PR
colorbar boolean was not used in imshow
added contour labels to the countour plot
removed debug code
Fixed spelling
contourlabel -> label_contour
Merge pull request #596 from chrisboo/colorbar_2d_hist

Optionally add a color bar to the 2D matplotlib plots created with hist2d and imshow