Allow import/export of XenCenter configuaration file

[TwoWheelDev]

XenCenter allows you to export your server list as an xml file. We should have the option to both import and export these. Sample:

<?xml version="1.0" encoding="utf-16"?>
<XenConnections>
    <XenConnection>
        <Hostname>beta.internal.serverb.co.uk</Hostname>
        <Port>443</Port>
        <FriendlyName>beta.internal.serverb.co.uk</FriendlyName>
    </XenConnection>
</XenConnections>