Integrate demo geometry (pivot.geojson for example) inside code

[nkarasiak]

For now the package has not geometry example in order to test and try directly a geometry. The geometry (pivot.geojson) is just a geojson file inside the examples folder, so not available when downloading the notebooks. That can be very useful to have it inside the code (see sklearn datasets)

[robmarkcole]

@nkarasiak based on previous experience, having the files in the repo is preferable to external download links which can break. However these should be kept lightweight

[nkarasiak]

Implemented in since v0.0.1-rc5 #17