OAuth2 Gmail

Added OAuth2 GMAIL loggin/logout support.
      Added OAuth2 Gmail filter.
LoginModule
      Updated LoginModule with OAuth2 Gmail support.
Persitence
      Extended user persitance api with OAuth2 gmail features.
      (TODO refactor persistance as an user extention)

examples/demo/site/scripts/oauth_gmail.sql

@@ -0,0 +1,14 @@
+BEGIN;
+
+
+CREATE TABLE "oauth2_gmail"(
+   "uid" INTEGER PRIMARY KEY NOT NULL CHECK("uid">=0),
+   "access_token" VARCHAR(255)  NOT NULL,
+   "created" DATETIME NOT NULL,
+   "details" TEXT NOT NULL,
+   CONSTRAINT "uid"
+    UNIQUE("uid")
+   );
+
+
+COMMIT;