Update to version 2, which adds several features (timsainb#46)

* update to v2

* updated readme

* updated noisereduce logo

* updated noisereduce logo

* added tests

* added tests

* added tests

* added tests

* updated tests

Co-authored-by: Timothy J Sainburg <[email protected]>

upick update to notebook

Add GPU acceleration (timsainb#14)

* added pad clipping flag

* added tensorflow backend

* updated docstrings

* updated readme

* updated readme

* updated package version

* updated readme

* updated readme

* updated website

* updated testing

* updated testing and black formatting

* update testing

* added test requirements

* updated travis yml to install requirements-txt

* updated travis yml

* updated test-req

update readme