Revert "path: resolve normalize drive letter to lower case"

This reverts commit f6e57401.

Changing drive letters to lowercase violates the principle of
least surprise. Other functions that do this should get fixed too.

Conflicts:
	lib/path.js

PR-URL: https://github.com/iojs/io.js/pull/100


Reviewed-By: Bert Belder <bertbelder@gmail.com>