Bump version to 0.2.1
Bump version to 0.2.1

Fixed a legit crash and a memory leak. Added CFFI to Travis.
terrelln/python-zstandard,indygreg/python-zstandard,indygreg/python-zstandard,indygreg/python-zstandard,terrelln/python-zstandard,indygreg/python-zstandard,terrelln/python-zstandard,terrelln/python-zstandard