Implemented "packages to be removed"
This will allow us to install connman instead of NetworkManager in
Razor-qt and E17.

It reads from the XML file the conflict package as an argument
(E.g:
<pkgname nm='true' name='connman' conflicts='netctl'>
qconnman-ui
</pkgname>)

Then the list is sent (in case of more than one) to pac.py which
discards the conflict packages when building the transaction.