Create Pool test suite

[schakrava]

Create a set of tests for operations on pool
Raid0 tests:

1. Add pool with raid0, 2 disks -- should succeed
2. Add pool with raid0, 0 disks -- check for appropriate error
3. Add pool with raid0, 1 disk -- should succeed
4. Add pool with raid0, 5 disks -- should succeed

Raid1 tests:

1. Add pool with raid1

Raid10 tests:

1. Add pool with raid10

Pool resize:

1. Add one disk to an existing pool
2. Add zero disks to an existing pool

Every add pool test should have a generic delete pool test to delete the pool, which should always succeed