libguestfs.tests: Add test module for partition operations.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
libguestfs.tests: Add test module for volume operations.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
libguestfs.tests: Add test module for virt_inspect_operations.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
pool_create: Resolve test errors

Originally posted to virt-test before the commit as PR 1236:

https://github.com/autotest/virt-test/pull/1236

This replaces and resolves issues mentioned from review. The main
difference between this version and the last one posted previously
is that the code now handles the transient 'default' storage pool
not being started prior to the test being run in the "error" case.
I also cleaned up and commented more the finally logic.
find_storage_pool_sources_as: Check for required utilities

In order to run the iscsi and logical tests, the 'tgtadm' and
'iscsiadm' utilities must be installed; otherwise, tests fail.
Add check and skip if not installed.
Add try/except for login_iscsi and create_vg failure

Add a try/except for login_iscsi or create_vg failure.  If the login_iscsi
fails, then we leave with the iscsiadm still logged in if the creation
of the vg fails.  If either fails, then use the exception to propagate
the error.
Merge pull request #18 from will-Do/find_pool_sources

libvirt.test: Add test for virsh find-storage-pool-sources
Merge pull request #33 from jferlan/storage_pool_sources_as

find_storage_pool_sources_as: Check for required utility
Merge pull request #25 from jferlan/pool_create

pool_create: Resolve test errors
Merge pull request #35 from yumingfei/virt_part_oper

libguestfs.tests: Add testcases.
libvirt.tests: Re-write virsh_pool.py to cover more pool types and commands

    1. Expend case to cover more pool types
    2. Expend case to cover more virsh pool commands
    3. Remove the vol-create/delete part which can be covered in virsh
       volume testing

Signed-off-by: Yanbing Du <ydu@redhat.com>