Add support of hidden files to folder list model.

Property 'ShowHidden' has been added to see hidden files.

Task-number: QTBUG-34247.
Change-Id: I7016b04b9d29731139c32bc0b30b93762e03e02e
Reviewed-by: Alan Alpert <aalpert@blackberry.com>
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Fix adding created objects to instantiator.

Before all new objects were pushed into the end of QVector,
i.e. if item model changes object with low index newly created object
will be added like it has big index. So, removing objects from
instantiator was buggy.

Task-number: QTBUG-33847.
Change-Id: I49fba53a40fce72060b629f737c10b525c67cc86
Reviewed-by: Alan Alpert (Personal) <416365416c@gmail.com>
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Cleanup QML specific JS code generator

Move parameters global to the entire QML file to the constructor, pass
component/context specific parameters to the generate function.

Change-Id: I6c3ab41b3bab19b066bbe20f971c5cafaeb70b98
Reviewed-by: Lars Knoll <lars.knoll@digia.com>