VcsManager: Add unit tests

Add some unit tests to the VcsManager to test the detection and
caching of version control systems.

Change-Id: I2b3f9218c12aebde8a8120fc869efc76c36ae41a
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/coreplugin/coreplugin.h

@@ -57,6 +57,12 @@ public:
 public slots:
     void fileOpenRequest(const QString&);
 
+private slots:
+#if defined(WITH_TESTS)
+    void testVcsManager_data();
+    void testVcsManager();
+#endif
+
 private:
     void parseArguments(const QStringList & arguments);