Added GridPlot for bokeh backend
Added GridPlot for bokeh backend

mjabri/holoviews,mjabri/holoviews,vascotenner/holoviews,basnijholt/holoviews,vascotenner/holoviews,vascotenner/holoviews,ioam/holoviews,basnijholt/holoviews,mjabri/holoviews,ioam/holoviews,basnijholt/holoviews,ioam/holoviews