Upgrade to Kiwi 2.2.2

Also add Podfile.lock and remove it from gitignore
Refactor internals using facade for keychain services
A more robust way of handling Keychain errors

An instance of `LUKeychainAccess` may be optionally given a error
handler, which can be any object that implements the
`LUTestErrorHandler` protocol. This error handler will be notified if an
error occurs.