Ostafen Clover Versions Save

This version brings important changes to the core of the library.

• Documents are now serialized using gob
• Support for int64/uint64, time.Time and []byte
• Possibility to write criteria with conditions involving multiple fields
• Minor fixes and improvements

This release adds several improvements, fixes and useful utilities:

• Sorting
• Skip/Limit criteria
• JSON inport/export
• An in-memory StorageEngine
• More detailed documentation
• UpdateById() and ReplaceById() methods
• Save() method