Nullify php-fpm log spam

[clpetersonucf]

This is a single-line addition to the materia-app dockerfile to prevent the php-fpm access.log contents from making it into the docker stream. These logs don't appear to ever contain anything useful and cause massive bloat of the application logs on production.

Note that since this modifies the materia-app image, the local image must be rebuilt. docker-compose down will not suffice since that only kills containers, not images.