Removed requirements_dev.txt and requirements_pip.txt as they are not needed anymore.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>

requirements_dev.txt

-bumpversion
-coverage
-cryptography
-flake8
-pip
-PyYAML
-Sphinx
-tox
-watchdog
-wheel

requirements_pip.txt

-folium>=0.6.0,!=0.12.0
-geojson
-plotly