Move Package['python-software-properties'] to apt:ppa

[tbroyer]

python-software-properties is only needed by apt::ppa, not any of the other puppet-apt types or classes, so let's move it to apt:ppa, so it only gets installed if needed.

This also allows dependencies like this one, where the apt-proxy, sources.list et al., and the apt-get update, are guaranteed to be set/have run prior to installing the package:

class { 'apt':
   # set proxy or whatever other option here
}
apt::ppa { 'ppa:...':
   require => Class['apt']
}

Also updates the apt-update in Apt::Ppa to use $apt::params::provider instead of aptitude.

[bodepd]

this needs to be in double quotes so that the variable apt::params::provider is interpolated
also, for clarity, I would be explicit about the namespace

"${::apt::params::provider} update"

[tbroyer]

Oops, of course!

Commit amended. Also changed other apt::params variables to be explicit about the namespace.

[branan]

This no longer merges cleanly. I've opened #54 which contains a rebased version of this request.