[Users] Update Zimbra OpenPGP Zimlet to 2.3.8

[Barry De Graaff]

Hello All,

Zimbra OpenPGP Zimlet has been updated to 2.3.8.

Improve pgp mime parser and various improvements
- improve pgp/mime mime parser
- add support for gpgit (https://gitlab.com/mikecardwell/gpgit)
- display more information to,cc and date when printing messages
- fix bug in time converter to display leading zeros in time for to/cc/print feature
- fix a bug where a public keys with mutliple userId's and one userId = null breaks pubKeySelect 
- add/update jsdoc style comments
- fix help links (2.3.7)


Regards, Barry