[openstack|compute] update volume tests
[core] exclude :headers from symbolization for real this time; added better tests; Thanks @burns!
Fix up the 'disk' api

A recent patch to introduce support for creating disks from
snapshots had a few problems:
1. Incorrect URL (to the snapshot resource) was being sent
2. Ruby syntax errors.

I looked into adding Shindo tests for this, but am not able to
since this request relies on a pre-existing snapshot which we
use for disk creation.
Merge pull request #2066 from burns/openstack_volume_tests

[openstack|compute] update volume tests
Merge pull request #2068 from maginatics/gce_fix_disk_from_snapshot

[google|compute] Fix up the 'disk' api
Fix some issues with GCE examples and disk requests.
Fix comments in Google snapshot example.
Merge pull request #2069 from icco/random-bugs

[google|compute] Fix some issues with GCE examples and disk requests.
Merge pull request #2067 from rackspace/header_fix2

[core] exclude :headers from symbolization for real this time
[openstack|compute] update flavor tests

- Update mocks and reorder tests so both live and mocked tests pass.
- Ensure #remove_flavor_access sends `tenant_id` as a String.
  If sent as an Integer, the server will return 500.
  (#add_flavor_access works either way)
[openstack|storage] Added temporary signed URL support
Merge pull request #2070 from burns/openstack_compute_flavor_tests

[openstack|compute] update flavor tests
Merge pull request #2071 from snoopie/openstack_signed_url

[openstack|storage] Added temporary signed URL support