Removed unused imports in ipython/display_hooks.py
Removed unused imports in ipython/display_hooks.py

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