add Annotation method to get an annotation

[mdb]

This adds a convenience method for fetching an individual
annotation. Note that the Grafana API
documentation documents no method for paging through results.

This addresses issue #47 .

[mlclmj]

In general I'm wary of adding convenience functions to our public API, and a little hesitant about this since it doesn't map to an actual HTTP method from grafana. I think really the best option is to add this to Grafana and use the method here, but in the meantime is there a way to implement this where a user wouldn't need to specify the search filter to get an annotation?

[mdb]

@mlclmj Thanks for your feedback! I just want to make sure I understand...

In general I'm wary of adding convenience functions to our public API, and a little hesitant about this since it doesn't map to an actual HTTP method from grafana.

☝️ Am I correct in interpreting this to mean that you're wary of creating go-grafana-api functions (what I call methods above) that don't map directly to existing Grafana API endpoints/capabilities?

I think really the best option is to add this to Grafana and use the method here

☝️ Am I correct in thinking you're suggesting that a GET /api/annotations/:id endpoint be added to the Grafana API itself?

but in the meantime is there a way to implement this where a user wouldn't need to specify the search filter to get an annotation?

☝️ Could you elaborate a bit on what you mean here?

[mdb]

@mlclmj @tonglil Can you offer any update on my above-posted questions? I completely understand if you're hesitant to merge this PR, though I'm curious to learn more about your views. Having a better understanding of your design vision could help me better design beneficial, merge-able contributions in the future. Thanks!