tests: Fix test failures for Local storage and Basic (SG) zones
* Skip migrate vm when localstorage enabled
* Fix test_direct_download.py
* Skip test_03_create_network_domain_network_offering in basic zones
* Skip test_03_create_vpc_domain_vpc_offering in basic zones
* Skip test_01_add_primary_storage_disabled_host if localstorageenabled
* Remove constraint for NFS storage
* Add new property on agent.properties
* Add free disk space on the host prior template download
* Add unit tests for the free space check
* Fix free space check - retrieve avaiable size in bytes
* Update default location for direct download
* Improve the method to retrieve hosts to retry on depending on the destination pool type and scope
* Verify location for temporary download exists before checking free space
* In progress - refactor and extension
* Refactor and fix
* Last fixes and marvin tests
* Remove unused test file
* Improve logging
* Change default path for direct download
* Fix upload certificate
* Fix ISO failure after retry
* Fix metalink filename mismatch error
* Fix iso direct download
* Fix for direct download ISOs on local storage and shared mount point
* Last fix iso
* Fix VM migration with ISO
* Refactor volume migration to remove secondary storage intermediate
* Fix simulator issue
* Add revoke certificates API
* Add background task to sync certificates
* Fix marvin test and revoke certificate
* Fix certificate sent to hypervisor was missing headers
* Fix background task for uploading certificates to hosts
* Improvements on upload direct download certificates
* Move upload direct download certificate logic to KVM plugin
* Extend unit test certificate expiration days
* Add marvin tests and command to revoke certificates
* Review comments
* Do not include revoke certificates API
