Fix notebook extensions install error
Fix notebook extensions install error

Fix for #292.

e-koch/mpld3,jakevdp/mpld3,kdheepak89/mpld3,etgalloway/mpld3,aflaxman/mpld3,kdheepak89/mpld3,mpld3/mpld3,etgalloway/mpld3,jakevdp/mpld3,e-koch/mpld3,aflaxman/mpld3,mpld3/mpld3