Add a cache system on the referential info

+ Add an identity service

Back/skydiveLogs-api.DomainBusiness/Interfaces/IIdentityService.cs

@@ -0,0 +1,9 @@
+using skydiveLogs_api.Domain;
+
+namespace skydiveLogs_api.DomainBusiness.Interfaces
+{
+    public interface IIdentityService
+    {
+        User ConnectedUser { get; }
+    }
+}