Port the webslice Plasmoid to Plamsa 5.

In Plasma 4 we had a plamsoid that showed a webpage as a widget that could be placed on the desktop.

http://cdn.ghacks.net/wp-content/uploads/2010/08/webslice.png

This needs recreating for plasma 5. The old code is mostly useless, and the new code needs to be redone in QML.

This should be mostly a template QML plasmoid with a http://qt-project.org/doc/qt-5/qml-qtwebkit-webview.html taking up most the plasmoid with a RowLayout with some buttons

For now ignore the config page bookmarks and zooming. They can be a future task.

Ask in #plasma if you have any problems.