[qtmozembed] Call init() immediately if mozcontext already intialized.

Creating a QmlMozView dynamically was failing because initialization code
path was relaying on sceneGraphInitialized signal which was not
emitted once application was running. Multiple QmlMozView that
were declared in qml or at application startup were working
previously.
Merge pull request #57 from rainemak/initFix

[qtmozembed] Call init() immediately if mozcontext already intialized.