Handling unlimited values when updating quota

Changes:
- Adding a general approach to handle unlimited values when performing
calculations with quota values.
- New test that fails without the fix.
- Updated test cases to support the fix.

Change-Id: I762a8e67261c0e0286307832cd13ad12e6d96504
Closes-Bug: #1292494
Use the list when get information from libvirt

If the libvirt adds new elements to the domain info struct or others,
when use the new libvirt, there will be a valueError (too many values
to unpack). When we get information from libvirt, we should use the
original variable format. This change is for compatibility with upcoming
versions of libvirt which change this signature.

Change-Id: I0271a260a53fe8f5fc17b2934ebe3a3c9ee0c130
Closes-Bug: #1291805
VMware: clean up VNC console handling

Commit 61bfac8881dd6a71a572a54b2ea1680248fc4bc4 introduced
the VMwareVCVMOps class. This class specifcally treats VC methods.
The patch set moves the treatment for get_vnc_console to this
class.

The log message for the VNC console now has the instance as a
parameter.

Please note that there are already test cases for this.

Change-Id: I2b943558d96328580f5c8744945e5f5f1790c06f
Merge "Use the list when get information from libvirt"
Merge "VMware: clean up VNC console handling"
Merge "Handling unlimited values when updating quota"