Revert "Removed dependency for QtWebKit. Added temporary dependence for MapTiler GUI custom WebBrowser - using native WebKit on Mac OSX. Fixed for Qt 4.8 version"

This reverts commit 4361142c96647f674237ea0f07295a8ce6706030.
Revert "Set HTTP user agent in order to fix behavior on Qt 5.1 and static files served by sourceforge.net"

This reverts commit 9980f27babbb895844921139c57f839c7e84391b.