Add Liquid 0.5.1-beta

Signed-off-by: Miguel M. Almeida <miguelcma@CMA-Retina.local>
Remove unnecessary #to_s

Signed-off-by: Miguel M. Almeida <miguelcma@CMA-Retina.local>
Merge pull request #11547 from miguelcma/master

Add Liquid 0.5.1-beta