Add resource_count

[gordalina]

Adds a new optional variable resource_count which asserts that the number of resources created are equal to the given value. When this variable is not defined, no check is made.

Fixes #4

[ericchiang]

This check is there to make sure the next line returns something sane

selflink := data.Items[0].Metadata.Selflink

To support multiple resources, we'd want to track all the returned selflinks and encode them in the ID.

[gordalina]

@ericchiang pushed a commit to address your comment

[ericchiang]

Thanks! Unfortunately, terraform plugins also need to read the self link data when performing a delete, and to determine if the resource still exists remotely. You can see the code here:

	resource, namespace, ok := resourceFromSelflink(d.Id())

So more of the plugin needs to change to handle the new ID format. The ID format also needs to be backward compatible. The plugin has to understand old IDs as well for data that's already been persisted.

Give me a sec. I can make the changes.

[gordalina]

Awesome, appreciate it!

[ericchiang]

Can you take a look at #21 and maybe test it?

[gordalina]

Closing in favor of #21 and #23