text: Title: Choropleths, tooltips/popups and pandas dataframes
  Body: **Is your feature request related to a problem? Please describe.**
  Sorry if this has been resolved already or if I'm missing something obvious. I'm pretty new to Folium and this is my first time posting a question/request on github. I think I have seen this issue mentioned before but I'm uncertain if solutions where implemented or rejected.
  
  I have been trying to wrap my head around how to create polygon specific popups or tooltips when creating choropleth-map. I would like to display data concerning the specific region from the dataframe in a popup or tooltip when clicking or hovering the pointer over the region on the map. 
  
  As far I understand the documentation it is only possible to display information that's in the GeoJson using `folium.features.GeoJsonTooltip`. The problem with that solution is that you need to merge the data from the pandas dataframe into the GeoJson, which goes against the convenience handling the data in pandas and the geographical data in GeoJson. 
  
  I have tried using both a `folium.Choropleth` object and making my own using `folium.GeoJson`.
  
  Is there some example of how this could be achieved using Folium and regular pandas?
  
  **Describe the solution you'd like**
  I would like to be able to code something like this to access data from the pandas dataframe:
  
  ```
  m = folium.Map(location=[lat, long], width=600, height=1000, zoom_start=5)
  
  choro = folium.Choropleth(
          geo_data=GeoJsonshape,
          name='Unemployment',
          data=dataframe,
          columns=['region', 'rate'],
          key_on='feature.properties.name',
          legend_name='Unemployment'
          tooltip=dataframe['rate'].where([feature['properties']['name']]
          )
  
  choro.add_to(m)
  ```
  
  or
  
  ```
  choro = folium.GeoJson(
          GeoJsonshape,
          name='Unemployment',,
          tooltip=dataframe['rate'].where([feature['properties']['name']],
          style_function=lambda feature: {
          'fillColor': colormap(data[feature['properties']['name']]),
          'color': 'black',
          'weight': 1,
          'fillOpacity': 0.6,
          'line_opacity': 0.2,
      }
      )
  ```
  
  
  **Describe alternatives you've considered**
  Another solution I think would be to use Geopandas to join the GeoJson with the dataframe, but this is not practically feasible solution for me. Geopandas is dependent on GDAL. My current environment makes it more or less impossible to install this. 
  
  If anyone can give me any pointers on how to solve this I would be grateful. I have tried to look at the folium code to perhaps implement a work around for myself but it is above my current ability. 