RegressionTest: Fixes to regression testing system to make it run

correctly on Ubuntu 12.04 - fixed size of grabbed image. Side effect is
that the default window size for ResInsight is increased slightly.
Removed parameter to image comparison tool to allow running regression
tests on RedHat 5

ApplicationCode/RiaMain.cpp

@@ -30,11 +30,7 @@ int main(int argc, char *argv[])
     RiuMainWindow window;
     QString platform = cvf::System::is64Bit() ? "(64bit)" : "(32bit)";
     window.setWindowTitle("ResInsight " + platform);
-#ifdef CVF_LINUX
-    window.resize(1000, 806);
-#else
-     window.resize(1000, 800);
-#endif
+    window.setDefaultWindowSize();
     window.show();
 
     if (app.parseArguments())