DateTimePicker library updated to v3.1.3

Hi, 

recently I have tried install the otp.js library and I have found some problems:

* `DateTimePicker` library in `local` folder gets errors with latest version of `moment` library
* `--verbose` tag in Makefile is deprecated, now component uses `--debug`
* `--prefix '.'` creating scripts references to `.local/` instead `local/`

I have found and strange issue, `make` operation to build client, overwrites `local/bootstrap/fonts` with symbolic links, and I can't understand why this.

Regards.