Fix handling of filesystem paths

[techalchemy]

Filesystem paths shouldn't be explicitly bytes encoded, but instead should be filesystem encoded and decoded according to sys.getfilesystemencoding() and should have error handling according to sys.getfilesystemencodeerrors() where available, surrogatepass on windows+python 3.2+, replace when encoding on windows+python2, escape when decoding on windows+python2, and surrogateescape on posix when getfilesystemencodeerrors() is not available.

[techalchemy]

Closed by #54