Update CentOS6 install instructions for GitLab 8.9

Added caddy web-server recipe

Adjust some of the DB stuff

Replicated on Fresh FreeBSD 10 install

Turns off NoEscape flag. Adapted from https://gitlab.com/gitlab-org/gitlab-ce/issues/3163

Comment to change config files to use full path

gitlab/config and gitlab-shell/config had symbolic links (/home/*), but they needed to be full paths (/usr/home/*) for pushing from command line and adding files from the web browser.

(Fix found at https://github.com/gitlabhq/gitlabhq/issues/8703 and worked or me.)

systemd: remove unused (for 8.2.x onwards) files.

systemd: update gitlab-workhorse for 8.3.x.

systemd: add unit for gitlab-workhorse.

Please note that this deprecates the gitlab-git-http-server used for
8.0-8.1. Gitlab Workhorse is used from 8.2 and hopefully onwards.

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/1919

unify Apache config files, fix missing RewriteCond lines for gitlab-workhorse in non-omnibus configs
(8 conf files with almost the same content easily run out of sync)

When getting an archive from the API, the ID can be NAMESPACE/PROJECT_NAME
http://gitlab.mycompany.com/api/v3/projects/foo%2Fbar/repository/archive.zip?sha=87a5db5ea887763fa3a31a5471b512ff1596d9b8

The Apache option "NE" avoids double encoding of the %2F