Adding Gemfile

- Removing redundant deve dependencies
Revert "Fix UserManager.load"

This reverts commit 79cfe0ec9a0a660d04a79ab5d6404ebc20baec0c.
Adding rspec
Fix user spec
Fix manager yield spec
Fix UserManager#to_yaml
Add support for ruby 1.9.3

- User#to_yaml now correctly outputs the encrypted string