Add new port `editors/encryptpad', a minimalist secure text editor and
binary encryptor.

WWW: http://evpo.net/encryptpad/

Because GitHub releases (tarballs) are not fetched with correct modification
time, set TIMESTAMP to 1484432907 which corresponds to commit c9e6636 tagged
as this release.

PR: 215639
Submitted by: Dmitri Goutnik