Add option to specify conflicts

[alejandroalfonsoyero]

In debian/contro file template, include the Conflicts section

https://www.debian.org/doc/debian-policy/ch-relationships.html

Ex:

debian/control

Package: {{ node_deb_package_name }}
...
Maintainer: {{ node_deb_package_maintainer }}
Description: {{ node_deb_package_description }}
Conflicts: some-conflict-package, other-conflict-package # From template definition in package.json