Attempt to connect to vCenter
        :return:

def vcenter_connect(self):
        """
        Attempt to connect to vCenter
        :return:
        """
        try:
            si = SmartConnect(
                host=self.host,
                user=self.user,
                pwd=self.password,
                port=self.port)
            # disconnect vc
            atexit.register(Disconnect, si)
        except vim.fault.InvalidLogin as e:
            print "Unable to connect to vcenter because of: {}".format(e.msg)
            sys.exit(5)
        return si