esx: Add support for the VMXNET 2 (Enhanced) NIC model

Add a test case and document it.

tests/vmx2xmldata/vmx2xml-ethernet-vmxnet2.vmx

@@ -0,0 +1,9 @@
+config.version = "8"
+virtualHW.version = "4"
+ethernet0.present = "true"
+ethernet0.virtualDev = "vmxnet"
+ethernet0.features = "15"
+ethernet0.networkName = "VM Network"
+ethernet0.connectionType = "bridged"
+ethernet0.addressType = "static"
+ethernet0.address = "00:50:56:11:22:33"

tests/vmx2xmldata/vmx2xml-ethernet-vmxnet2.xml

@@ -0,0 +1,20 @@
+<domain type='vmware'>
+  <uuid>00000000-0000-0000-0000-000000000000</uuid>
+  <memory>32768</memory>
+  <currentMemory>32768</currentMemory>
+  <vcpu>1</vcpu>
+  <os>
+    <type arch='i686'>hvm</type>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <interface type='bridge'>
+      <mac address='00:50:56:11:22:33'/>
+      <source bridge='VM Network'/>
+      <model type='vmxnet2'/>
+    </interface>
+  </devices>
+</domain>