Improved OpenNebula support

This patch improves Fog's OpenNebula support in a number of ways:
Better NIC support in VM templates
Better ability to tune number of CPUs and memory
Ability to add/remove entries from a VM template's context section
Ability to add/remove entries from a VM template's user variables
Improved filtering for templates and NICs
[cloudstack] Add get volumes for server
[cloudstack] Add get snapshots for volume
[cloudstack] Add reset_password for server
Modularized Voxel Provider
Bump the API version for DynamoDB put
Rescue if IO throws exception on attempted #rewind

This will permit the passing in of pipes, sockets, or other IO objects that
throw exceptions when you call the #rewind method.
Merge pull request #3253 from plribeiro3000/voxel

Modularized Voxel Provider
Merge pull request #3261 from elkelk/master

Bump the API version for DynamoDB put
Improved OpenNebula support

This patch improves Fog's OpenNebula support in a number of ways:
Better NIC support in VM templates
Better ability to tune number of CPUs and memory
Ability to add/remove entries from a VM template's context section
Ability to add/remove entries from a VM template's user variables
Improved filtering for templates and NICs
Merge pull request #3246 from giddie/glacier-pipe-data

Don't attempt to rewind IO if it's not offset
Merge pull request #3256 from hermanator/additional_cloudstack_assotiacions

[cloudstack] Extend server interface
Moved Vmfusion to its own gem
Merge pull request #3264 from plribeiro3000/remove_vmfusion

Moved Vmfusion to its own gem
[AWS|IAM] Do not call Fog.mock! in tests
[AWS|IAM] Also ignore Fog::AWS::IAM::NotFound (and return nil)
[AWS|IAM] Fix assigning path to IAM role
[AWS|IAM] Fix user count tests (there will be at least 1 other user on the account for fog access)
Updating authentication functions to prevent sending expired token.
        Fix Dynect job poll bug.

        Dynect sometimes gives back HTTP 200 instead of 307.
        https://github.com/Netflix/denominator/issues/261

        We need a workaround for this until it is fixed.