Fix Huawei drivers to support other host OSs

Huawei drivers create Linux hosts by default when attaching volumes.
This patch makes them also support Windows, XenServer, AIX, etc.
The default OS is still Linux if it is not specified.

Users need to configure the host OS types in Huawei XML configuration
file. They need to set the items like this:
<Host OSType="Windows" HostIP="10.10.0.1, 10.10.0.2, ..." />
<Host .../>

When attaching a volume, the driver will get the host IP from nova. We
compare that IP with the IP in "HostIP" to get the corresponding OS type.

Closes-bug: #1229759

(cherry picked from I36fd52b97f790f1c68eaf24b6c12e7ef5d16145d)

Change-Id: I6792aaae050b126088447a0df65e10c425b84102
Merge "Fix Huawei drivers to support other host OSs" into stable/havana