VNC customisations

Several updates to VNC:
- Added to README
- Converts tests to bool per PR feedback
- Cut out the specification of all optional fields in <graphics> and
removed <video> xml

Author: goetzk

README.md

@@ -60,6 +60,9 @@ Role Variables
 
     - `clock_offset`: Overrides default set in `libvirt_vm_clock_offset`
 
+    - `enable_vnc`: If true enables VNC listening on localhost for use with
+      VirtManager and similar tools
+
     - `volumes`: a list of volumes to attach to the VM.  Each volume is
       defined with the following dict:
         - `pool`: Name or UUID of the storage pool from which the volume should be

templates/vm.xml.j2

@@ -76,15 +76,10 @@
       <target type='serial' port='0'/>
     </console>
 {% endif %}
-{% if enable_vnc %}
-    <graphics type='vnc' port='5906' autoport='yes' listen='127.0.0.1'>
+{% if enable_vnc |bool %}
+    <graphics type='vnc' autoport='yes' listen='127.0.0.1'>
       <listen type='address' address='127.0.0.1'/>
     </graphics>
-    <video>
-      <model type='cirrus' vram='16384' heads='1' primary='yes'/>
-      <alias name='video0'/>
-      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
-    </video>
 {% endif %}
   </devices>
 </domain>