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
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
[vSphere] Support clusters that are located below folders
[vSphere] Support non-clusters setup
[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.
Clusters lists tests
        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.
Merge pull request #3267 from nsidc/master

        Fix Dynect job poll bug.
Adding Tests and Mocks

Adding several test cases for flavors and updating network tests to
support new attributes.
Merge branch 'opennebula' of github.com:blackberry/fog into opennebula

Conflicts:
	fog.gemspec
	lib/fog/opennebula/models/compute/networks.rb
	lib/fog/opennebula/requests/compute/list_networks.rb
Merge remote-tracking branch 'upstream/master' into opennebula

Conflicts:
	fog.gemspec
Fixing merge conflict
Removing version dependency
Merge pull request #3265 from mikehale/fix-1322

Fix 1322
Handle Docker authentication errors

Fog was not handling at all the error returned by docker-api. This
commit fixes that and raises an AuthenticationError that can be caught
by Fog clients.

There was a bug in the errors code for container_action that this PR
fixes too.
clarify getting started README

closes #2148