start to move session stores into there own key value in memory store

src/store/store_errros.go

@@ -0,0 +1,8 @@
+package store
+
+import "errors"
+
+var ErrKeyNotFound = errors.New("Key not found")
+var ErrKeyAlreadyExists = errors.New("Key already exists")
+var ErrKeyExpired = errors.New("Key expired")
+var ErrKeyBackend = errors.New("Key backend")