VMware vSphere support

(*) Copied the following utility files to execute vSphere queries from
'cinder'. These common utility files are going to be converted to a
library as a part of blueprint 'vmware-api' but till then these files
will be used as it is.

   api.py,
   error_util.py,
   vim.py,
   vim_util.py

(*) Using the above mentioned utilities, implemented a wrapper class for
querying performance stats from VC.

Change-Id: I445bcdb3f8ac240d1799bfd31f8b888982d7d97f
Implements: blueprint vmware-vcenter-server
(cherry picked from commit c81c800ee09d4e5ac33992073938450406984d07)

Conflicts:

	ceilometer/compute/virt/vmware/vim.py
	ceilometer/compute/virt/vmware/vsphere_operations.py

Change-Id: I27be83ebbbef08727f6fda509e58d1b5f8849e2a
Updated the TestVcConnection.py