hob: eliminate the "by recipe" grouping in the packages table
We have agreed to change how we show the packages. Now they are not grouped by
recipe. Until now, it was implemented using TreeStore and I've changed it to
extend a ListStore. I have modified all the function in according to this.
[YOCTO #2180] Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>