Use cmake-js instead of gyp

[vjpr]

https://github.com/cmake-js/cmake-js

Might make things simpler and avoid the python2 dependency from gyp.

[savearray2]

Thanks for the suggestion!

I haven't looked much at cmake-js recently. I think I took a look at it a (very) long time ago. It would be nice to lose the python2 dep.

I'll take a look at this if the library gains more traction. :)