indent using 4 spaces (1/3)

As advised in I072cf8bf6748d0c910fecffdf2282bcc4656d038, code should
use 4 spaces for indentation.

This commit enforces the use of 4 spaces indentation.
In order to simplify the review process, this patch only cover the
following elements:
 - bm-dnsmasq,
 - boot-stack,
 - cinder-volume
 - devstack
 - haproxy
 - keepalived
 - mariadb
 - mariadb-dev
 - memcached
 - mysql-common
 - mysql

Change-Id: I7932fd24e72f7585e24ad3e0213f42361e668f7c