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
Fix display_name of volume for test_volumes_list

In test_volumes_list, three volumes are created for some tests.
These display_name seems wrong like "volume-%s1393726625json".
The interface name should be inserted after "volume-", but it is
appended to the tail.
This patch fixes this volume name.

Change-Id: Iee55d2405e888569455a2325fe6b2843ddf9de9d
Merge "add admin server tests"
Merge "Fix display_name of volume for test_volumes_list"