addresses gitlabhq/gitlabhq#3809

Setting Git's global user.name and user.email are missing from
instructions, causing check.rake to fail at this step.

Signed-off-by: Axilleas Pipinellis <axilleas@archlinux.gr>

Signed-off-by: Axilleas Pipinellis <axilleas@archlinux.gr>

By default there is no public/uploads directory when no attachments
are uploaded. Prompt users to create the uploads directory during
install otherwise the backup task will fail.

Place mysqldump args in single quotes to avoid error if password
contains special characters.

Signed-off-by: Axilleas Pipinellis <axilleas@archlinux.gr>

For some reason, if the nginx configuration is bound to an IP, it breaks the install, causing all git clone/push/pull operations to die with a 'fatal: The remote end hung up unexpectedly' message. Changing this configuration seems to fix the problem. I reckon that this is just a temporary fix. I don't know the ins and outs of GitLab well enough to vouch for this change, but I do know that these instructions are broken, and that this update will fix them.

Move init.d and nginx default recipes in core library to save efforts trying keep sync between gitlab-recipes and gitlabhq

Removing duplication by putting everything in the readme. Allow us to close issues that deviate from the guidelines.

Allow connection to Redis via unix socket, using
unix:/var/run/redis/redis.sock for example.

Default behaviour does not change, except that the full Redis URL must
be configured, with redis:// for tcp or unix: for unix socket.

changed installation overview list step #4
Gitolite -> GitLab shell 

Added creation of pids directory to fix #2995, replaced deprecated nginx init.d command with service one, some more clean-up

Made it a bit clearer what step 5 is for to stop people skipping it. This time with a relative link.