[openstack] Refactor Openstack Authentication

Signed-off-by: Nelvin Driz <nelvindriz@live.com>
[opnestack|identity] Added set_tenant request for identity service
[openstack|identity] use tenant_id parameter in users model
[openstack] Make use of the unscoped token for reauthentication
[Brightbox] Fixes test to run out of sequence

Interface requests were using existing servers to examine the format
of the API response but that meant the test had to run when servers
existed. If no servers exist we create one, test it and destroy it.
[Brightbox] Expands documentation for Compute class
[openstack|identity] Add `attr_accessor :unscoped_token` to Mock

Signed-off-by: Nelvin Driz <nelvindriz@live.com>
[openstack|compute] Add "Reset Server State" request
[openstack|compute] Add `get_limits` request

Signed-off-by: Nelvin Driz <nelvindriz@live.com>
Fix public_key attribute to be visible in table.
Merge pull request #1302 from fog/add_user_agent

[core] Adds fog User-Agent header
Merge pull request #1298 from bodepd/add_group

Add attr group.
Merge pull request #1305 from vdemeester/1304_volume_pool_name

Add support for volume_pool_name
Merge pull request #1278 from ohadlevy/vmware

[vsphere] ensure reload works correctly for server
[openstack] Fix Typo in Merge of Authentication Refactoring

Signed-off-by: Nelvin Driz <nelvindriz@live.com>
[Brightbox] Tests recognised options

Never actually tested the options we declared when creating a new
instance of the Compute service.
Merge pull request #1307 from Keoven/update/openstack-module

[openstack] Bulk Update
Revert "[core] Adds fog User-Agent header"

This reverts commit a07f3203a6d501d8091495ddd475213ce9d84912.

The change made a dependency on Fog::VERSION which is defined in
`lib/fog` forcing more of the system to be loaded in some cases.

Github issue #1310
[core] Splits Fog::VERSION into own file

Now available within "fog/core"

Just reverted a change where depending on Fog::VERSION for the
User-Agent made a dependency on requiring "lib/fog" which also requires
all providers and services.

That is highly undesirable from a modular perspective!
[core] Adds fog User-Agent header

As discussed in #1026 this adds a User Agent HTTP header to help identify
the version of fog is accessing APIs.

This revised version fixes issue #1310