Windows test related changes

- adapted some tests to use an arbitrary path separator to make sure we use the defined separator
- faked split(), dirname(), walk(), realpath(), adapted relpath() to fix these tests
- fixed case sensitivity for cygwin

Author: mrbean-bremen

CHANGES.md

@@ -16,6 +16,7 @@ The release versions are PyPi releases.
  * support for `glob.iglob`
 
 #### Fixes
+ * shutil.move incorrectly moves directories (#145)
  * Missing support for 'x' mode in `open` (Python >= 3.3) (#147)
  * Incorrect exception type in Posix if path ancestor is a file (#139)
  * Exception handling when using `Patcher` with py.test (#135)