added dummy parse_setup_cmd() function and some (failing) tests for it
tests pass. probably a few more hard cases to get right
better handling of shell punctuation
removed parse_hash_path()
added resolution of env vars and ~ in path
made nice docstring
changed tests to require that parse_setup_cmd() include trailing slashes
as part of the command (3 tests now fail)
updated parse_setup_cmd() to include trailing name slash in cmd. Added
another test to make this explicit
Merge branch 'parse_setup_cmd' of github.com:davidmarin/mrjob