Improve the image pipeline

[stuartlynn]

• Find a way to center the building in question.
• Have the zoom be more consistent so the building is clearer
• Filter out small buildings
• Expand this to more regions / generate more data

[ciupava]

• improve the logic behind the images generation

[ciupava]

PS: the images generation is currently done using the code in notebooks/evaluate.py and in images_processing.ipynb.
The current images are limited by the data availability (as explained in the current version of the initial README), but the improved data will look ideally more like the validate projects in MapSwipe Web, i.e.:

• centered on the building
• possibility to zoom in/out
• possibility to view/unview the polygon

See example below:

i.e.:

Looping in also @kshitijrajsharma and @Hagellach37