Move duckpan.js (spice2_duckpan_compile.js) into DuckPAN sharedir

cc/ @nospampleasemam @russellholt 

Currently DuckPAN makes a request for the file `spice2_duckpan_compile.js` which is a small JS script created for DuckPAN to compile the Spice templates and now to properly display Goodies.

https://duckduckgo.com/spice2/spice2_duckpan_compile.js

There is no need for this file to be requested over the web, and seeing as DuckPAN is the only thing using it, I figure it might as well live in the DuckPAN repo.