Update Readme.markdown
Adding support for kSecAttrSynchronizableAny

Changed the synchronizable property to the type
SSKeychainQuerySynchronizable with the possible options of
SSKeychainQuerySynchronizableNo/Yes/Any.
Adding test for the synchronizable property
Renaming the SSKeychainQuerySynchronizable type

From SSKeychainQuerySynchronizable to SSKeychainQuerySynchronizationMode
Merge pull request #53 from blommegard/master

Adding support for kSecAttrSynchronizableAny
Happy New Year 🎉