Fix invalid behavior when setting invalid or callable array notifier

v0.2.2

Bump version for release

Fix inconsistent hash in SplObjectStorage

v0.2.1

Bump version for release

Add array notifier and fix comparison

Fixes and cleanups.

Here are some of them:

• add array notifier;
• fix weakrefs compariosn;
• monkey-patch spl hashes;
• fix weakrefcounted to be true only when weakrefcount > 0.

Initial release

Initial release with development environment (Vagrant).