do not fully ignore git directory when building docker images
".git/HEAD" and ".git/refs/heads/*" are required by "getVersion()" in "lib/Configuration.php" to build the version string
* Switch Docker Image to official php base image
Switch from the unofficial Alpine+php image to the official php-apache image.
This has 2 advantages:
1. Official image is guaranteed to have regular updates, etc
2. The persistent Docker Alpine DNS Issue goes away;
https://github.com/gliderlabs/docker-alpine/issues/255
* [Docker] Ignore more files from Docker Image
