Delete instance faults when deleting instance

Instance delete should also delete related record from the
instance_faults table.

Change-Id: I9c845bce6cf39003858a1b2a726734db9fb9e584
Closes-bug: #1237155
libvirt: Set "Disabled Reason" to None when enable nova compute

When use "nova host-update" to enable nova compute, the column of
"Disabled Reason" will be set as empty, this will make the
"Disabled Reason" is not consistent with other services.

+------------------+------+----------+---------+-----------------+
| Binary           | Host |   Zone   |   ...   | Disabled Reason |
+------------------+------+----------+---------+-----------------+
| nova-conductor   | jay1 | internal |   ...   | None            |
| nova-cert        | jay1 | internal |   ...   | None            |
| nova-scheduler   | jay1 | internal |   ...   | None            |
| nova-compute     | jay1 | nova     |   ...   |                 |
| nova-consoleauth | jay1 | internal |   ...   | None            |
+------------------+------+----------+---------+-----------------+

The fix was set the "Disabled Reason" to None when enable a nova
compute.

Change-Id: Ief1f21ba450812a240d30104624bcec92e3f989e
Partial-Bug: #1251803
lxc: Fix a bug of baselineCPU parse failure

When starting nova-compute on compute node with lxc hypervisor,
a valueError exception will be raised because a libvirt bug of
the incorrect return value of baselineCPU() function, in function
get_host_capabilities, which introduced by commit
3b8c26321bce07b8ad588099c1fdcef858e748a8.

For libvirt interface baselineCPU() in python library, -1 will be
returned if basecpu info is None from version 1.1.2, and the return
value of this interface is corrected to None from version 1.2.0.

So a checking is added to make sure the return value of baselineCPU()
is not -1, and also a test case is added.

Closes-bug: #1259796

Co-authored-by: Wangpan <hzwangpan@corp.netease.com>

Change-Id: I5e4cb4a8d09b660edc4f6c6a4ad4bfe58a4dd5cb
Merge "libvirt: Set "Disabled Reason" to None when enable nova compute"
Merge "Delete instance faults when deleting instance"
Merge "lxc: Fix a bug of baselineCPU parse failure"