Implemented legend handling for Overlays in bokeh
Implemented legend handling for Overlays in bokeh

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