Validation and AutoMapper

Removed FluentValidation, in favour of DataAnnotations and a custom
DataAnnotations validator for use in all layers (not just MVC).
Also removed redundant IMappingConfigurations in favor of AutoMapper.
Also added more specs.
[OTF:1619] TranslationService SaaS using the CQRS model
[OTF:1619] TranslationService SaaS using the CQRS model