WelcomeScreen: Clean up tag browser

- Always show tag browser button
- Make tag browser button a toggle (popup semantics)
- Remove "Clear" Button

Change-Id: Ic1f6894103fdc14973c230764ffb06574dd1897b
Reviewed-on: http://codereview.qt.nokia.com/2048
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Daniel Molkentin <daniel.molkentin@nokia.com>

src/plugins/welcome/welcomeplugin.cpp

@@ -63,7 +63,7 @@
 #include <QtDeclarative/QDeclarativeEngine>
 #include <QtDeclarative/QDeclarativeNetworkAccessManagerFactory>
 
-enum { debug = 1 };
+enum { debug = 0 };
 
 using namespace ExtensionSystem;