#414 Add domain model for metadata

api/pom.xml

api/src/main/java/fitconnect/api/data/Attachment.java

api/src/main/java/fitconnect/api/data/Data.java

api/src/main/java/fitconnect/api/data/Metadata.java

...tconnect/api/domain/metadata/AdditionalReferenceInfo.java

...onnect/api/domain/metadata/AuthenticationInformation.java

...java/fitconnect/api/domain/metadata/ContentStructure.java

...rc/main/java/fitconnect/api/domain/metadata/Metadata.java

...va/fitconnect/api/domain/metadata/PaymentInformation.java

...ava/fitconnect/api/domain/metadata/PublicServiceType.java

...ain/java/fitconnect/api/domain/metadata/ReplyChannel.java

...fitconnect/api/domain/metadata/attachment/Attachment.java

...va/fitconnect/api/domain/metadata/attachment/Purpose.java

...omain/metadata/attachment/signature/EidasAdesProfile.java

...ect/api/domain/metadata/attachment/signature/Hash__1.java

...domain/metadata/attachment/signature/SignatureFormat.java

...pi/domain/metadata/attachment/signature/Signature__1.java

...onnect/api/domain/metadata/attachment/signature/Type.java

...c/main/java/fitconnect/api/domain/metadata/data/Data.java

...fitconnect/api/domain/metadata/data/EidasAdesProfile.java