Implement virtual management commands.

This is part one of a six part changeset that implements a command for listing images. This command outputs a list of all images that are available to use for provisioning.
Implement virtual management commands.

This is part one of a six part changeset that implements a command for listing images. This command outputs a list of all images that are available to use for provisioning.
Merge branch 'review' of https://github.com/MSOpenTech/azure-sdk-for-ruby into review
spell check
Merge pull request #60 from MSOpenTech/review

Adding List Images command