Extend getPolyAStandardizedSignal

- add mode change between median and mean
- standardization parameters can be added as parameters

cleanup after creating docs

Remove commented python versions

pod5 available via conda

Move python version requirement to 'python_requires'

Try to add test files to sdist

Fix Conda package build tests

Fixed Imports of Conda Package

Update README.rst as long description

Add README.rst as long description