Added gem versions. Added pry-rails gem.
Adds JsonSchemaValidator
Pluralizes property name in schema when multiple values possible
Validates ContentItem's :content with JsonSchemaValidator
Merge remote-tracking branch 'origin/content_items' into content_items

Conflicts:
	spec/fabricators/content_item_fabricator.rb
Updates API::V1::ContentItems POST/PUT :content to be Hash