Minor fixes to Evan's work on Issue #97 ( tokenByTokenAndConsumer )

'Cached' which method ( tokenByTokenAndConsumer or tokenByConsumer)
the provider is providing, and stopped testing for the token methods
for *each* required method in the loop (typo.)

lib/auth.strategies/oauth/_oauthservices.js

@@ -63,19 +63,25 @@ exports.OAuthServices= function(provider, legs) {
   **/
   requiredMethods.forEach(function(method) {
     if(!(Object.prototype.toString.call(provider[method]) === "[object Function]")) throw Error("Data provider must provide the methods [" + requiredMethods.join(', ') + "]");
-
-    if(this.legs == 3 &&
-       !(Object.prototype.toString.call(provider.tokenByConsumer) === "[object Function]") &&
-       !(Object.prototype.toString.call(provider.tokenByTokenAndConsumer) === "[object Function]")) {
-        throw new Error("Data provider must provide either tokenByConsumer() or tokenByTokenAndConsumer()");
-    }
   });  
+
+  if(this.legs == 3) {
+    this.providerProvidesTokenByConsumer= (Object.prototype.toString.call(provider.tokenByConsumer) === "[object Function]");
+    this.providerProvidesTokenByTokenAndConsumer= (Object.prototype.toString.call(provider.tokenByTokenAndConsumer) === "[object Function]");
+    if( !this.providerProvidesTokenByConsumer && !this.providerProvidesTokenByTokenAndConsumer) {
+      throw new Error("Data provider must provide either tokenByConsumer() or tokenByTokenAndConsumer()");
+    }  else {
+
+    }
+  }
+
+
 };
 
 exports.OAuthServices.prototype.tokenByTokenAndConsumer= function(token, consumerKey, callback) {
-  if (Object.prototype.toString.call(this.provider.tokenByTokenAndConsumer) === "[object Function]") {
+  if (this.providerProvidesTokenByTokenAndConsumer) {
     this.provider.tokenByTokenAndConsumer(token, consumerKey, callback);
-  } else if (Object.prototype.toString.call(this.provider.tokenByConsumer) === "[object Function]") {
+  } else if (this.providerProvidesTokenByConsumer) {
     this.provider.tokenByConsumer(consumerKey, callback);
   } else {
     callback(new Error("provider: must provide either tokenByConsumer() or tokenByTokenAndConsumer()"), null);