conf: Add support for modifying ssl validation for https/ftps disks

To allow turning off verification of SSL cerificates add a new element
<ssl> to the disk source XML which will allow configuring the validation
process using the 'verify' attribute.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

tests/genericxml2xmlindata/disk-network-http.xml

@@ -25,6 +25,7 @@
       <driver name='qemu' type='raw'/>
       <source protocol='https' name='test2.img'>
         <host name='example.org' port='443'/>
+        <ssl verify='no'/>
       </source>
       <target dev='vdb' bus='virtio'/>
     </disk>
@@ -35,6 +36,14 @@
       </source>
       <target dev='vdc' bus='virtio'/>
     </disk>
+    <disk type='network' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source protocol='https' name='test4.img'>
+        <host name='example.org' port='1234'/>
+        <ssl verify='yes'/>
+      </source>
+      <target dev='vdd' bus='virtio'/>
+    </disk>
     <controller type='usb' index='0'/>
     <controller type='pci' index='0' model='pci-root'/>
     <input type='mouse' bus='ps2'/>