Fix salt 2019.2 breaking change using yaml filter

[necabo]

With the salt 2019.2.0 (Fluorine) release there has been a non-backward-compatible change to the yaml renderer.

This PR addresses that change by using the yaml filter where necessary.

[vutny]

Thanks, @necabo
Similar patches were submitted to some repos in Salt Formulas, it's good we have one more formula compatible with latest stable Salt release.

[myii]

Thanks for this PR, @necabo.

@vutny In terms of consistency with the other fixes, would it be appropriate to use | json instead? Or is | yaml required specifically in this case?

[necabo]

Or is | yaml required specifically in this case?

I can assure that both | json and | yaml work for the pillar I tested with (example pillar).

[myii]

@necabo Thanks for testing that. There is a long history of changes related to this issue and the consistent option we have selected is to use | json. Of course, there are situations where | json doesn't work and we will use | yaml instead. Unless that's the case here, would you mind changing this PR to use | json instead? That will help us come back to these, when the eventual solution of | tojson needs to be considered for implementation. Refer back to saltstack-formulas/consul-formula#40 (comment) and the linked content there for more info.

[myii]

@necabo @vutny Merged, thanks to you both.