CLOUDSTACK-2067 - ACS4.2 - throw LibvirtException instead of squelching it

so that callers of startVM in LibvirtComputingResource know that a vm failed
to start

Signed-off-by: Marcus Sorensen <marcus@betterservers.com> 1366224775 -0600

plugins/hypervisors/kvm/src/com/cloud/hypervisor/kvm/resource/LibvirtComputingResource.java

@@ -1077,8 +1077,7 @@ ServerResource {
             */
             conn.domainCreateXML(domainXML, 0);
         } catch (final LibvirtException e) {
-            s_logger.warn("Failed to start domain " + vmName + ": "
-                    + e.getMessage(), e);
+            throw e;
         }
         return null;
     }