CLOUDSTACK-4994. Cannot attach VMwareInstallerISO to VMs that are of guest operating system CentOS 6.1 CentOS 6.2 CentOS 6.3 CentOS 6.4.
Cause - This issue can occur in VMware setups if the guest operating system is not specified when we install the virtual machine. In which case, since we map the OS to 'Other OS', VMwareInstallerISO attachment fails.
Added the necessary guest OS mapping for VMware.
fixed indentaion problem in utils.py :359

Conflicts:
	tools/marvin/marvin/integration/lib/utils.py