fixes #6527 / BZ 1115955 - activation keys - filter host collections by organization

When a user requests 'available host collections' for an activation key,
it should only show those that are available within the same organization
as the activation key being queried for.
Merge pull request #4403 from bbuckingham/issue-6527

fixes #6527 / BZ 1115955 - activation keys - filter host collections by organization