Old error message was awful in case of ip is icmp down.
In this patch:
* Method `wait_for` is replaced by `wait_for_statuses`, since `wait_for` is
deprecated and will be removed in near future;
* Representation of ready statuses for TimeoutException is changed(
example: `to become set(['ok', 'success']) -> `to become ('ok', 'success')`)
* All logic related to `host` is moved to separate class, since it is just
a helper and doesn't relate to VMUtils class and scenarios.
Error message before this patch:
Rally tired waiting for IPAddress IPAddress('172.24.4.16'):<no id> to become ICMP UP current status NONE
After:
Rally tired waiting for Host ip:172.24.4.16 to become ('ICMP UP') current status ICMP DOWN
Change-Id: I4d950bfd097731611188dc7f302fedbb83669a39
d90ab5e8b5