Remove chosen javascript

Seems like we are not using this anywhere:

$ grep -irl chosen .
./.git/index
./adagios.spec
./adagios/settings.pyc
./adagios/settings.py
./adagios/media/external/select2/README.md
./adagios/media/external/chosen/chosen.proto.min.js
./adagios/media/external/chosen/chosen.css
./adagios/media/external/chosen/chosen.proto.js
./adagios/media/external/chosen/README.md
./adagios/media/external/chosen/LICENSE.md
./adagios/media/external/chosen/chosen.jquery.min.js
./adagios/media/external/chosen/chosen.jquery.js