Added the code that will load and populate the Tank Info

Added the code that will load and populate the Tank Info
ComboBox that`s used by the user to select the Cylinder
description.

Code curerntly implements more than the GTK version since
the GTK version of it was a plain-list, this one is a
table based model that can be used in ListViews ( like
we use now in the ComboBox ) but also in TableViews
( if there`s a need in the future to see everything
that`s catalogued in the Tank Info struct. )

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>