added call to logout endpoint

lib/src/base/parse_constants.dart

@@ -7,6 +7,7 @@ const String keyLibraryName = 'Flutter Parse SDK';
 // End Points
 const String keyEndPointUserName = '/users/me';
 const String keyEndPointLogin = '/login';
+const String keyEndPointLogout = '/logout';
 const String keyEndPointUsers = '/users';
 const String keyEndPointVerificationEmail = '/verificationEmailRequest';
 const String keyEndPointRequestPasswordReset = '/requestPasswordReset';

lib/src/enums/parse_enum_api_rq.dart

@@ -12,6 +12,7 @@ enum ParseApiRQ {
   currentUser,
   signUp,
   login,
+  logout,
   loginAnonymous,
   verificationEmailRequest,
   requestPasswordReset,

lib/src/objects/parse_user.dart

@@ -200,11 +200,35 @@ class ParseUser extends ParseObject implements ParseCloneable {
     }
   }
 
-  /// Removes the current user from the session data
-  logout() {
-    _client.data.sessionId = null;
-    unpin(key: keyParseStoreUser);
-    setObjectData(null);
+  /// Sends a request to delete the sessions token from the
+  /// server. Will also delete the local user data unless
+  /// deleteLocalUserData is false.
+  logout({bool deleteLocalUserData = true}) async {
+    if (deleteLocalUserData) {
+      _client.data.sessionId = null;
+      unpin(key: keyParseStoreUser);
+      setObjectData(null);
+    }
+
+    try {
+      if (username == null) return null;
+
+      Uri tempUri = Uri.parse(_client.data.serverUrl);
+
+      Uri url = Uri(
+          scheme: tempUri.scheme,
+          host: tempUri.host,
+          path: "${tempUri.path}$keyEndPointLogout");
+
+      final response = await _client.post(
+        url,
+      );
+
+      return _handleResponse(
+          this, response, ParseApiRQ.logout, _debug, className);
+    } on Exception catch (e) {
+      return _handleException(e, ParseApiRQ.logout, _debug, className);
+    }
   }
 
   /// Sends a verification email to the users email address