ENH: add option for bgcolor in plot_topo
Expose new functionality in an example
STY: cb_color -> font_color, remove axis_facecolor in plot_topo_image*, cb axis off
Merge pull request #1536 from mainakjas/topo_background

merged after commit https://github.com/mainakjas/mne-python/commit/2ecc8fd25351e9f751327c927fcfb5b0c211c8dd#diff-d41d8cd98f00b204e9800998ecf8427e