Create User entity

backend/src/main/java/de/hft/geotime/user/User.java

@@ -1,4 +1,30 @@
 package de.hft.geotime.user;
 
+import lombok.Data;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+
+@Data
+@Entity
 public class User {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private long id;
+    private String username;
+    private String firstname;
+    private String lastname;
+    //TODO: roleid(FK)
+    //TODO: timetrackaccounts[List]
+
+    protected User() {
+    }
+
+    public User(String firstname, String lastname) {
+        this.firstname = firstname;
+        this.lastname = lastname;
+    }
 }