Allow checks to specify entity_label attributes.

[tildedave]

This allows checks to unambiguously refer to an
entity (similar to how alarms unambiguously refer
to their associated checks).

[tildedave]

I ran into a few issues using the CM cookbook to create new entities. Trying to determine how best to contribute fixes back, please let me know what's appropriate/not appropriate.

It appears that on using a check the cookbook assumes that node['cloud_monitoring']['entity_id'] is set.

However when an entity is newly created this value is not set and the check assignment immediately fails. By allowing specifying entity_label in a check you can unambiguously look up the entity.

(I did investigate ways to possibly set node['cloud_monitoring']['entity_id'] after entity creation but due to how LWRPs work it looked really bad.)

There's another issue where entities step on each other -- have one entity, entity_id gets set, define a second entity, it renames the current entity to the next one. Will have a PR for that once I figure out a reasonable fix.

[philk]

This seems safe and beneficial. +1

[philk]

Bump the version in metadata.rb then good to merge.