Add duck duck go plugin.
Fix require in MakeMeASandwich spec.

The actual plugin file was renamed, but the spec was still
referencing the old filename.
Merge pull request #12 from rjackson/add_duck_duck_go_handler

Add duck duck go plugin.
Merge pull request #13 from rjackson/fix_make_me_a_sandwich_spec

Fix require in MakeMeASandwich spec.