Fix for mysterious warning "Could not create directory ." on Hostmaster site Verify.
Use strict checks: is_file() and/or is_link() instead of file_exists() before attempting unlink()
Add little debugging markers.
Remove redundant file_exists() if is_readable() is also used.
Use is_readable() check instead of insufficient file_exists() for config includes.
Use is_dir() instead of file_exists() when checking directory existence.
Use is_readable() instead of file_exists() when checking alias existence.
Remove whitespace.
Remove legacy subdir code and update checks.
Shorten and simplify the subdirs checks code.
Fix typo.
Backport provision_hosting_feature_enabled()
Backport provision_hosting_feature_enabled (2)
Merge remote-tracking branch 'origin/6.x-2.x' into 2.3.x-dev

Conflicts:
	http/Provision/Config/Apache/vhost.tpl.php
	http/Provision/Config/Nginx/vhost.tpl.php
	http/Provision/Service/http/apache.php
	http/Provision/Service/http/nginx.php
Sync with upstream.