fixes #5601, #5603 - host-collections: add support for update and add/remove-content-host

This commits add support for the following commands:

host-collection update
host-collection add-content-host
host-collection remove-content-host
Merge pull request #163 from bbuckingham/issue-5601

fixes #5601, #5603 - host-collections: add support for update & add/remove-content-host