qt5webkit: reimplement the persistent cookie storage for the Qt platform

The facade pattern approach allows for a customized storage location and has been ported from an in-house developed patch
qt5webkit: remove commented-out code
qt5webkit: update facade

simplify the interface and add soup support
qt5webkit: remove cookie storage from qwebsettings

soup cookie storage has been moved to the facade
qt5webkit: make persistent cookie jar part of QWebSettings

a browser now can use 'QWebSettings::enablePersistentCookieStorage(QString path)
qt5webkit: revert to 'old' WebCore.pri

SharedCookieJar symbols are referenced and, thus, will not be removed
qt5webkit: fix non-soup build

there was an extra '+'-character
qt5webkit: initialize cookie storage path

explicitly initialize full path name instead of using append
qt5webkit: improve cookie storage

Assert on an attempt to create multiple cookie jars or use of an empty (invalid) full filename
Merge pull request #5 from Metrological/cookiejar

qtwebkit: more advanced cookie jar