[Ruby - In Review] Adding kind property on the resource model in ms_rest_azure.

[vishrutshah]

This is to resolve issue https://github.com/Azure/azure-sdk-ruby/issues/18.

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[veronicagg]

If 'kind' becomes part of resource, we may not need a 'fixme' comment.

[vishrutshah]

@veronicagg I completely agree but i haven't found any swagger other than web doing this, so i was thinking to keep it until 'kind' officially becomes part of all resource.

[devigned]

Kind is in this storage spec. Thoughts?

[vishrutshah]

@devigned I see the "kind" but it is not part of the Resource definition. azure_arm_web is adding "kind" in the resource itself. Isn't that different?

[veronicagg]

@vishrutshah left one comment, change looks good to me, thanks!

[vishrutshah]

@veronicagg @devigned Thanks for the feedback. Closing this PR with respect to #1263 that'll avoid failures on unknown properties of the object while serializing.