rename Password class to ShadowHash and adjust namepsace, tests, etc. as
required; also rename files
rename SimplePasword class to Password; mv/rename edit related files and
directories and modify related tests
move #convert_to_blob into Password module
move #convert_to_hex into Password module
update README
remove .rvmrc; better off using the system Ruby 2.0 for dev
Merge tag '0.0.3'

- mostly re-org
- renamed some classes
- migrated some methods