Add aggregate commands

* Add aggregate: add host, create, delete, list, remove host, set, show

* Add list --long option
* Filter 'availability_zone' from the metadata fields
* Rename 'metadata' column to 'properties' in all output

Bug: 1172032
Blueprint: nova-client

Change-Id: Icd408c2b34af07f5102f53d3778d8546952a12c5
Merge "Add aggregate commands"