add admin server tests

- use regular user to resize vm in test_resize_server_using_overlimit_*
- rebuild server when it's in SHUTOFF and ERROR state
- add parameter 'raise_on_error' in wait_for_server_status

Change-Id: Ibd04a1fdaab74fe59bcf16cc99d4ecf4821f4ae2
Merge "add admin server tests"