Refactored OAuth support for merge into master. fixes #84, #211

Cleaned up @rodchile's excellent work integration OAuth 1.0 and 2.0 into RestKit. Changes
are as follows:

* Introduced new RKRequestAuthenticationType to replace the forceBasicAuthentication and other
    methods for influencing how authorization works.
* Moved TDOAuth code into Vendor/
* Renamed authorization code flow classes and delegate methods for clarity.

Examples/RKTwitter/Classes/RKTwitterAppDelegate.m

@@ -18,7 +18,7 @@
 #pragma mark Application lifecycle
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
-//    RKLogConfigureByName("RestKit/Network*", RKLogLevelTrace);
+    RKLogConfigureByName("RestKit/Network*", RKLogLevelTrace);
     // Initialize RestKit
 	RKObjectManager* objectManager = [RKObjectManager objectManagerWithBaseURL:@"http://twitter.com"];
     

Examples/RKTwitter/Classes/RKTwitterViewController.m

@@ -19,7 +19,6 @@
     // Load the object model via RestKit	
     RKObjectManager* objectManager = [RKObjectManager sharedManager];
     objectManager.client.baseURL = @"http://www.twitter.com";
-
     [objectManager loadObjectsAtResourcePath:@"/status/user_timeline/RestKit" delegate:self block:^(RKObjectLoader* loader) {
         // Twitter returns statuses as a naked array in JSON, so we instruct the loader
         // to user the appropriate object mapping

Examples/RKTwitter/RKTwitter.xcodeproj/project.pbxproj

@@ -462,6 +462,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				BUILD_STYLE = Debug;
+				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "";
 				COPY_PHASE_STRIP = NO;
 				GCC_DYNAMIC_NO_PIC = NO;
 				GCC_OPTIMIZATION_LEVEL = 0;