Add non-conda install instructions

[philippjfr]

A user just posted these instructions for installing without conda, we should clean them up and document them properly:

# Install GDAL and Geopandas
!apt install gdal-bin python-gdal python3-gdal --quiet
!apt install python3-rtree --quiet
!apt install libgdal-dev libproj-dev --quiet
!apt install libgeos-dev
!pip install git+git://github.com/geopandas/geopandas.git --quiet
!pip install descartes --quiet
!pip install splot hvplot geoviews --quiet

[jlstevens]

Any thoughts on where such information should go? Talking to @jbednar, it sounds like we should have a 'Using HoloViz' page on holoviz.org where we can document 1) the jupyterlab extension 2) using other environments such as Colab, VSCode, Hydrogen etc 3) maybe mention alternative deployment options such as Django, Flask etc?

Then all the projects could point to this page. I also think it would be a good idea to show all the different platforms/ways you can use HoloViz in one place.

[philippjfr]

I was specifically thinking of adding a section on installing the heavy geo-dependencies for GeoViews without conda but I agree that HoloViz might be the most appropriate place to document how to use our tools in different environments (and in how far we support each) on HoloViz and then link to that section from all the installation and getting started guides.

[jbednar]

The "Using HoloViz" guide should also mention classic Jupyter, emphasizing both that we support it well and also that it is never required for any project.

[zouhx11]

I want to change a little bit of the code since shapely sometimes crashes colab:

!apt install python-cartopy python3-cartopy --quiet
!apt install gdal-bin python-gdal python3-gdal --quiet
!apt install python3-rtree --quiet
!apt install libgdal-dev libproj-dev --quiet
!apt install libgeos-dev
!pip install git+git://github.com/geopandas/geopandas.git --quiet
!pip install descartes --quiet
!pip install urbanaccess pandana pysal --quiet
!pip install splot hvplot geoviews --quiet
!pip install --no-binary shapely shapely --upgrade --force-reinstall --quiet

I have tested several times, it works like charm.

[bcgru]

It works perfectly. Thank you very much!!!