SessionsPolicy and sessions adaptor, history and _example written.

Former-commit-id: e8b0dde3cb3b72919f01b9d836d8ccb3d4e20214

adaptors/sessions/database.go

@@ -0,0 +1,17 @@
+package sessions
+
+// Database is the interface which all session databases should implement
+// By design it doesn't support any type of cookie session like other frameworks,
+// I want to protect you, believe me, no context access (although we could)
+// The scope of the database is to session somewhere the sessions in order to
+//  keep them after restarting the server, nothing more.
+// the values are sessiond by the underline session, the check for new sessions, or
+// 'this session value should added' are made automatically by q, you are able just to set the values to your backend database with Load function.
+// session database doesn't have any write or read access to the session, the loading of
+// the initial data is done by the Load(string) map[string]interfface{} function
+// synchronization are made automatically, you can register more than one session database
+// but the first non-empty Load return data will be used as the session values.
+type Database interface {
+	Load(string) map[string]interface{}
+	Update(string, map[string]interface{})
+}