phpLDAPadmin version bump to 1.2.6.7

[iamGavinJ]

IMPORTANT

The Dockerfile in this branch depends on osixia/web-baseimage:1.3.2 from a previous commit which has never been published. For this version to build either osixia/web-baseimage:1.3.2 needs to be published to Docker Hub, or the Dockerfile needs to be rolled back to osixia/web-baseimage:release-1.2.0-dev.

CHANGES

• phpLDAPadmin version bump to 1.2.6.7
• Added debug logging to build-nocache Makefile target
• Nginx signing keys updated: https://blog.nginx.org/blog/updating-pgp-key-for-nginx-software