Adding pym.js

Downloaded from https://github.com/nprapps/pym.js/.
Fixed version in pym.js

From
https://github.com/nprapps/pym.js/commit/c0a19a9161d7aa150f18b7d02e94936
d2bde0535
Merge pull request #3245 from cdnjs/pr/3182

Pr/3182