Merge pull request #58 from JonathanO/master

Detect attempts to instantiate interfaces or non-existent classes
Resolves #56 - Default JsonProperty "strict" to true

Fix stupid typo. The default was right for the legacy annotations, but not the Doctrine ones.
Merge pull request #59 from JonathanO/php-weasel-56

Resolves #56 - Default JsonProperty "strict" to true