lib/strategy: Add failWithError support

The failWithError option tells the strategy to not fail but pass instead
when authentication fails. This commit makes passport-jwt respect this setting.

Author: emdemir

lib/strategy.js

@@ -93,7 +93,11 @@ JwtStrategy.prototype.authenticate = function(req, options) {
     var token = self._jwtFromRequest(req);
 
     if (!token) {
-        return self.fail(new Error("No auth token"));
+        if (options.failWithError !== false) {
+            return self.fail(new Error("No auth token"));
+        } else {
+            return self.pass();
+        }
     }
 
     this._secretOrKeyProvider(req, token, function(secretOrKeyError, secretOrKey) {
@@ -110,7 +114,11 @@ JwtStrategy.prototype.authenticate = function(req, options) {
                         if(err) {
                             return self.error(err);
                         } else if (!user) {
-                            return self.fail(info);
+                            if (options.failWithError !== false) {
+                                return self.fail(info);
+                            } else {
+                                return self.pass();
+                            }
                         } else {
                             return self.success(user, info);
                         }