Py-ed25519-blake2b

Added pypy3 compatibility, thanks to Miroslav Shubernetskiy. Updated to
versioneer-0.15.

Added python3.3/3.4 compatibility, thanks to Jan Gerber. According to our
ongoing Travis-CI test coverage, we are now compatible with pythons 2.6, 2.7,
3.3, and 3.4 . Also updated to versioneer-0.11 (which supports py3).

Don't require C99 features that are lacking on some Microsoft compilers.
Thanks to Samuel "Dcoder" Neves for the patch, via pycryptopp.

Fix a segfault that occurred on 64bit systems, at least on Fedora/gcc-4.7,
resulting from using the wrong sized variable. Many thanks to Samuel "Dcoder"
Neves for tracking down the problem.

Minor changes: remove mention of the unimplemented base62 encoding, update to
versioneer-0.7 to make development smoother.

This release adds compatibility with python2.4, making this library
compatible with py2.4, 2.5, 2.6, and 2.7 . In the long run, our compatibility
target is probably 2.6 through 3.2, but py3 requires some deeper changes. In
the meantime, it'd be nice to have at least one version which can be used by
2.4 (this might be the last, though).