New version

Added missing extensions

Merge pull request #38 from KodyWiremane/issue-37

Fixes #37

Merge pull request #31 from KodyWiremane/issue-30

fixes #30

Added tests

Merge pull request #22 from MarcusSchwarz/issue-21

fixes #21

Added php 7.3 to travis.yml

Merge pull request #19 from hkarlstrom/master

Fix date format. Check’s that the date is a valid Gregorian date.

Merge pull request #18 from isd4n/master

Fix date-time format. It accepts date times without offset now.

Improved error handling for oneOf keyword