Add support for "local_hostname" key instance data

This patch adds support for querying instance data for the host name
with the "local_hostname" key.
diff --git a/DataSourceVMwareGuestInfo.py b/DataSourceVMwareGuestInfo.py
index 3c59406..c5da8f2 100644
--- a/DataSourceVMwareGuestInfo.py
+++ b/DataSourceVMwareGuestInfo.py
@@ -571,6 +571,7 @@
     if hostname:
         host_info['hostname'] = hostname
         host_info['local-hostname'] = hostname
+        host_info['local_hostname'] = hostname
 
     default_ipv4, default_ipv6 = get_default_ip_addrs()
     if default_ipv4: