Added intial spec for eZ template (twig) helper functions
EZP-23317 Twig Helper to get field Definition name in a template

Closes #980
EZP-23317 Twig Helper to get field Definition description in a template
EZP-23317 Twig Helper to get generic translatable properties in a template
Add integration tests for ez_field_value(), ez_content_name(), ez_field_name() & ez_field_description twig function
Optimize ContentExtension->getFieldTypeIdentifier() to avoid uneeded loadContentType()
Merge pull request #1030 from ezsystems/EZP-23317_good

EZP-23317 Twig Helpers to get translatable properties