core: StoragePoolValidatorTest initializers

Removed redundant initializers to solve IntelliJ IDEA warning.

Change-Id: Ifdf260ad7dafcbb1d9c1bbd7a3c6e375e74e18c7
Signed-off-by: Allon Mureinik <amureini@redhat.com>
core: StoragePoolValidatorTest assets

Standardized asserts to use ValidationResultMatchers in order to
improve readability and reuse code wherever possible.

Change-Id: Iae8ee38b15cdea9c876760bdc096c7adae578b8a
Signed-off-by: Allon Mureinik <amureini@redhat.com>
core: StoragePoolValidatorTest config mocking

Removed redundant mocking that's not used in the test and streamlined
the existing mocking to use two version - 3.0 as an "old" version which
does not support new features and 3.1 and a "new" version which does.

Related-To: https://bugzilla.redhat.com/1127590
Change-Id: If916e1080686ec037dba6f79264307e73b1502d2
Signed-off-by: Allon Mureinik <amureini@redhat.com>