Fix grafana_dashboards

[c10l]

This fixes #25, while also fixing syntax errors of some API requests and implements idempotency.

[bastelfreak]

looks good to me. Could someone with a bit more ruby knowledge review this as well?

[Sukiyakijango]

My question would be.. add a pull request when all the features are added by other previews request.. what is wrong with #23 and #17?

But from first look.. you removed in the Type the to_s def.. witch will cause that you will have the whole json outputed on each change.. the fix would be to use the is_to_s def..

[c10l]

I don't mind any of this being done as other PRs, but those don't seem to be merged because of outstanding issue.

I just thought perhaps if a cleaner PR with no issues would at least get the module in a working state, then the other features could be added in by those who need them.

I'm not sure I understand the is_to_s thing but I'll have a crack at it to see what I find out.

In the present state, this module is not very useful but with the fixes for the to_s method and the idempotency, it works for most use cases.

[roidelapluie]

LGTM, further improvements are now possible in other pull requests.

Thanks.