Fixed the encrypter
[4.2] Fixes mutators implementation when $mutatorCache for given class
is not available.

Solves #6769

Signed-off-by: crynobone <crynobone@gmail.com>
Additional fixes based on comment.

Signed-off-by: crynobone <crynobone@gmail.com>
Merge pull request #6771 from GrahamForks/4.2-fix

[4.2] Fixed The Encrypter
Merge pull request #6773 from crynobone/patch/mutator

[4.2] Fixes mutators implementation when $mutatorCache for given class is not available.
Spacing.
Use asset.
Tweak how key is checked.
Remove old tests.
Tag a new version.
fix fonflicts.