Date time validation fix

Fixed datetime input validation #30

2.3.2: Merge pull request #27 from LinioIT/hotfix/scalar-checks

Implemented more scalar checks to avoid errors during validation.

2.3.1: Merge pull request #26 from LinioIT/hotfix/not-string

Avoid breaking the code when variable is not a scalar.

2.3.0: Merge pull request #20 from lucianohosken/master

Added stictType to Enum constraint to support type validation

2.2.0: Merge pull request #16 from LinioIT/feature/schema-builder

Added schema builder

2.1.4: Merge pull request #17 from bycosta/master

Fix unpack error for arrays with string keys.