In order to optimise the distro package installation
process the list of packages to install is prepared
for the host in vars, instead of using two tasks.
A dynamic inclusion is used to further optimise the
execution of the package installation. The minimum
Ansible version is updated to 2.0 to provide for
the ability to do dynamic inclusions.
The package lists in defaults are removed as it is
undesirable to make it easy to override these lists.
This is not provided for in any other roles.
Change-Id: I71307d2a808fdc0f76e376a84651dad86b3f8b69
5a84473dc2