Make test_show_host_detail work with multi host installation

Get the host detail only if the host is compute host
and run the tests for all the compute host not just
for the first one.

Change-Id: I1830e6071c09d1e751048d74bd828d0eeac282f8
Closes-Bug: #1230000

Conflicts:
	tempest/api/compute/admin/test_hosts.py
Backport https://review.openstack.org/#/c/61037/

Change-Id: Icf75ca16ea43f7680c492bc780b1e66b94cc1a75
Backport https://review.openstack.org/#/c/63001/

Change-Id: I5c884d2848b7de9e4c26c90eabe8114200c10b21
Backport https://review.openstack.org/#/c/63446/

Use create_server from base.BaseComputeTest

This gets us for free the magic about using the right network.

Change-Id: I4b6cbf8243083cb377323a4aff8de305d5c300f9
Implement similar trick as https://review.openstack.org/#/c/63001/

Change-Id: Ib3ea97eddc0373f6f16bdd11715e265193a16626
Correctly initialize adminPass if using the default image

Change-Id: I477808c9a3ddb31cf81a31b24628400846b2b871