Support EC2 filters

Registered by justinsb

We should support EC2 filters, if for no other reason than for API compatibility with EC2.

However, this actually goes much further. I'm referencing here my proposed merge:
https://code.launchpad.net/~justin-fathomdb/nova/ec2-filters/+merge/53266

The patch was architected with a separation of the AWS filterspec from an underlying predicate, so it could also support filters in the OpenStack API if we can agree an API format.

(If we are going to discuss adding filter support to the OpenStack API, then I think we'll need a full "Discussion" session)

Taken further, these filters could dramatically simplify and harmonize a lot of our code, by using functions that take predicates rather than a long list of similar functions varying only in their arguments. (fetch_instance_by_id, fetch_instance_by_project, fetch_instances_for_user etc etc)

Blueprint information

Status:
Complete
Approver:
Vish Ishaya
Priority:
Undefined
Drafter:
justinsb
Direction:
Approved
Assignee:
None
Definition:
Obsolete
Series goal:
None
Implementation:
Deferred
Milestone target:
None
Completed by
Vish Ishaya

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