Handle case of not setting options; do not return options we don't set

[edestecd]

On OSX machines I have tested:

lib/puppet/provider/printer/cups.rb: blows up about calling include? on nil when you don't set options.
AND
Continues to try and set every possible option listed by lpoptions -l instead of just the options you pass as a hash.

This fixes both of those by putting back some code that was removed in the past.
I copied it, more or less, from the 1.3.0 branch.

[mosen]

Hey there,
There's a bit of a balancing act with options so I would like to add a test to replicate this first. I can never seem to guarantee that fixing options on OS X won't break ubuntu or vice versa.

[mosen]

FYI: Setting up OSX beaker test to repeat the issue as it isnt replicated on CentOS. Should be able to find some middle ground.