qemu: Add more test cases for usb devices

[zhouqt]

No description provided.

[jzupka]

I like this pull-request. Only some minor problems.

[zhouqt]

@jzupka Hi, new version sent.

[zhouqt]

@jzupka
I've marked this test as RHEL host only, so the software_manager module is unnecessary.
And for the sar package, I must keep this script work, without raising the TestNAError (It's really funny a script is written but can't be run).
BTW, all our internal hosts have this package installed.

If you don't like this solution, I can remove this separated patch from this pullreq, so that others can be merged.

[jzupka]

@zhouqt If you really need force this pull request to upstream please remove first patch b8b1459 and please repair it in new version. I like the idea of patch. With software_manager it could be really nice solution and check find_command should be good.
If all yours computers have installed sar then it doesn't end with TestNAError.

I though something like this:

try:
   find_command(sar)
except ValueError:
   software_manager = SoftwareManager()
   if software_manager.install(usb_sar_pgk):
        logging.info("Packages %s installed successfuly", usb_sar_pgk)
    else:
        logging.error("Failed to install %s", usb_sar_pgk)

[zhouqt]

@jzupka removed.

[jzupka]

Acked-by: @jzupka

[lmr]

Pushed to next, thanks guys!