release: v0.2.0

CHANGELOG:
- Use None instead of 0 if PID cannot be retrieved (BREAKING CHANGE)
- xucred: Store primary GID in separate field (instead of having it as a
  property that returns self.groups[0])
- Don't load libc using ctypes on Linux, where it isn't needed (adds
  support for statically linked systems)

unix_cred/__init__.py

@@ -5,7 +5,7 @@
 
 from . import ffi, util
 
-__version__ = "0.1.0"
+__version__ = "0.2.0"
 
 __all__ = ["get_peer_uid_gid"]