Improved deployments to non-cetera hosting environments

Prior to this change, we've struggled to deploy to external environments
 in case document root folder is not named "www". We need to either create
 a symlink or completely rewrite deploy job to make it work.
Both options required extra efforts from devops team, were error prone
 and symlink option is not reliable by itself: there are chances that
 symlink will be deleted and then deploy will be broken in terms of the
 results but the deployment job will be green, so it is hard to notice
 that something got broken.
Now we can rename DOC_ROOT to any arbitrary value, and this means
 we can deploy www to whatever folder name on the remote server we needed.