using genericmodel example code

based on example code how to implement QAbstractListModel
https://code.google.com/p/cellardoor/source/browse/?r=cd45960b47d3e9ae74132b56a54c727dd8c8c307#git/src
i tried integrating it with no avail.. trying something diffrent but
committing this stuff first
stuff compiles now, changed generalmodel stuff into using pointers
exposing database data successfull

got the example code working, still needs some cleanup before merging.
problem was getting roles, which represent properties of qml objects on
the c++/qabstractmodel side
clean up & .sql change again

commented out many functions. using qdjangoqueryset inside of
genericmodel instead of a handmade qlist. works so far but there are
performance woes.
added image_url fields to project and product table. moneycode got a
valid_until and in&out booking reference.
Merge remote-tracking branch 'origin/genericmodel-branch'