DuckSay: Only call the function if there is an argument.

So the old implementation was that `ddg_spice_duck_say()` was getting called every time, and the problem with that is it gets executed first before reddit even gets back to us.
DuckSay: fmt
Merge pull request #1114 from duckduckgo/jag/ducksay-call

DuckSay: Only call the function if there is an argument.