ppa_options not getting correct default

While working on updating unit tests for apt::ppa, found that if
apt::params hasn't already been included elsewhere, the $options
parameter is not picking up the correct defaults. Updated the code to
set default options after apt::params is included.
I'm not sure the apt class needs to be included before ppa is included though.  Later on in the file there is a check for if defined(Class['apt']) and the else isn't a fail.