Create base model

[janishorsts]

• Create base models in protobuf.
• Create base models in pkg/model package.
• Add pkg/transform to transform between protobuf generated models and pkg/model. E.g. transform.MessageFromProto() and transform.MessageToProtobuf().

type Message struct {
  ID        string
  Message   string
  Fuzzy     bool
}

type Messages struct {
  Language string
  Messages []Message
}