Update init.d script

The original init.d script uses a fixed username (e.g. git). Which is not flexible
when we using other user. So, I've updated it to use $APP_USER variable
instead and wrap it in a function to reduce repetitive codes.

Fix not using git.bin_path in config.

Add Gitlab::VersionInfo class to fix and simplify version check.

improve gfm autocomplete

It returns "yes" if required version is "1.7.10" and current version is "1.6.10",
because the patch version of current version equals to that of required version.

Setting the working directory before git operations

Puma configuration for relative base URL

Bump charlock_holmes to 0.9.6.4

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

Fix errors during backup task. Fix #3785

Code cleanup: Replace old hashes and remove trailing spaces

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>