Add action to resolve disk settings (#1502)

With multi volume boxes, need to ensure that disk settings such as the
device assigned are resolved dynamically once it has been established
which devices have already been assigned to the box volumes on either
initial creation or subsequent boots.

Otherwise users are forced to always explicitly define the device for
additional storage instead of having it be automatically assigned the
next available device.

Consequently previous changes have broken the ability for machines
with additional storage to be halted and restarted correctly.

Include an integration test that for additional storage checks that the
machine can be stopped and started again.

Fixes: #1490

locales/en.yml

@@ -58,9 +58,11 @@ en:
     remove_stale_volume: |-
       Remove stale volume...
 
-    destroy:
+    domain_xml:
       obsolete_method: |
-        Destroying machine that was originally created without device aliases (pre 0.6.0), using fallback approach.
+        Machine that was originally created without device aliases (pre 0.6.0), using fall-back approach for device identification.
+
+    destroy:
       unexpected_volumes: |
         Unexpected number of volumes detected, possibly additional volumes attached outside of vagrant-libvirt.
         Attempting to handle this correctly, however may experience unexpected behaviour in the domain destroy.