Don't pass options to ppa on lucid

Lucid (10.04) has `add-apt-repository` but it doesn't accept any
options. The define defaulted to `-y` but this changes that on lucid.

This was made 7 months ago, so apparently no one cares about 10.04 any
more.
Merge pull request #231 from hunner/fix_ppa_options

Don't pass options to ppa on lucid