Release 1.0.0

Production-ready release 1.0.0 with some new features and tests.

Changelog:

• BREAKING: Changed the behaviour on getting non-existent cache entries to returning/passing undefined instead of throwing/passing an error
• Implemented memory caching for better performance (configurable)
• Implemented unlinking
• Wrote tests :-)

Release 0.1.0

First release. Core functions work without known bugs, not marked as 1.0.0 (and thus production ready) due to missing tests.