Add test for vol-download and vol-upload

Signed-off-by: Kyla Zhang <weizhan@redhat.com>
libvirt.tests: Add virsh vol-create command case

Add test case for virsh command vol-create, prepare different type
of pools before run the command within the case.

The case covers pool of default format with supported volume format
matrix.

Reference:
http://www.libvirt.org/storage.html

Signed-off-by: Wayne Sun <gsun@redhat.com>
Merge pull request #65 from kylazhang/vol-upload-download

Add test for vol-download and vol-upload
libvirt.tests: Replace creating vol with PoolVolumeTest.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
Merge pull request #70 from waynesun09/vol_create

libvirt.tests: Add virsh vol-create command case
Add 4 cases to test following guestfish commands

blockdev-getbsz
blockdev-getsize64
blockdev-getss
blockdev-getsz