Applied fix for install_name_tool on #{opt_prefix}/lib/QtWebKitWidgets.framework/Versions/5/QtWebKitWidgets

I've fixed the install_name_tool calls to apply the same treatment to  `#{opt_prefix}/lib/QtWebKitWidgets.framework/Versions/5/QtWebKitWidgets`. The pre-existing install_name_tool commands were also doubly-specifying their paths and probably not working:

    ==> install_name_tool -change /private/tmp/default-LpbK/qt-everywhere-opensource-src-5.1.1/qt-everywhere-opensource-src-5.1.1/qtwebkit/lib/QtWebKitWidgets.framework/Versions/5/Qt
    ==> install_name_tool -change /private/tmp/default-LpbK/qt-everywhere-opensource-src-5.1.1/qt-everywhere-opensource-src-5.1.1/qtwebkit/lib/QtWebKit.framework/Versions/5/QtWebKit 
    ==> install_name_tool -change /private/tmp/default-LpbK/qt-everywhere-opensource-src-5.1.1/qt-everywhere-opensource-src-5.1.1/qtwebkit/lib/QtWebKit.framework/Versions/5/QtWebKit 

Now does:

    ==> install_name_tool -change /private/tmp/default-cpEp/qt-everywhere-opensource-src-5.1.1/qtwebkit/lib/QtWebKitWidgets.framework/Versions/5/QtWebKitWidgets /usr/local/Cellar/qt5
    ==> install_name_tool -change /private/tmp/default-cpEp/qt-everywhere-opensource-src-5.1.1/qtwebkit/lib/QtWebKit.framework/Versions/5/QtWebKit /usr/local/Cellar/qt5/5.1.1/lib/QtW
    ==> install_name_tool -change /private/tmp/default-cpEp/qt-everywhere-opensource-src-5.1.1/qtwebkit/lib/QtWebKit.framework/Versions/5/QtWebKit /usr/local/Cellar/qt5/5.1.1/lib/QtW

After installing using this updated formula PyQt works happily out of the box.