Fix date and datetime column displaying null values.

Currently null values display as today's date and time in the twigbuilder templates.
Update Admingenerator.es.yml

Single upload translation ES
Merge pull request #412 from ronzalo/patch-3

Update Admingenerator.es.yml
merged #409
Update installation-via-composer.md
Update installation-via-composer.md
changes of upload widget for sf 2.2.x #400
Merge remote-tracking branch 'origin/master'
Update composer.json
Allow multiple "NONE" group for fieldset
Fix SingleUploadType deprecated calls
Merge pull request #413 from sescandell/feature-multi_none_fieldsets

Allow multiple "NONE" group for fieldset
Merge pull request #414 from sescandell/fix-deprecated_calls

Fix SingleUploadType deprecated calls