Revert "re-enabled all the migrators"
back out change to sync with Ondrej

This reverts commit 62cb15e18c759aa0c59d54a529a26165f6c20393.
Revert "check of empty Batch object; Do not exec empty ones"
backout for resync

This reverts commit 5f40e7b7378f24f4381f5b9dfa4a1f455971e012.
Revert "MIGR-38: refactor; report only cli cmd to use"
back out change to sync with Ondrej

This reverts commit 62403d75b80b33cf3fce82eba74f79490fbdfd18.