when system VM ping times out, stop system VM
Revert "CLOUDSTACK-7647: Fix 'isReverse' checkboxes which are checked by default"

This reverts commit ef4b5d41b7dd9ba16afd04c7716bada4a4721f79.
add guest OS Centos 7 and Oracle Linux 7
Undo "Revert "CLOUDSTACK-7647"

This reverts commit 38bd1b934ef770e8a2993c8f42b3fff03484f266.