Using accessors, adding err checks

[ghost]

• Addresses Terraform plan does not detect updates when graphs updated outside terraform #20 and cannot unmarshal string into Go struct field Yaxis.min of type float64 after upgrading to 0.10.3 #19
• Most calls to schema.ResourceData.Set failed to check returned error, surpressing actual errors
• Zorkian's go-datadog-api.v2 uses accessor methods and not all the provider code was updated
• Switched to using kr/pretty logging to dump objects during debug
• Changed events, groups, and scopes from schema.TypeSet to schema.TypeList, there were errors that were resolved by moving to TypeList. I don't know if this was the right path, maybe we could revisit making these sets in the future. Errors were like this:

* module.datadog_timeboard.my_timeboard: datadog_timeboard.my_timeboard: Invalid address to set: []string{"graph", "2", "scope"}

[ghost]

I could go either way on using the kr/pretty package, if anyone is against it. I just find it easier to have better reflection when dumping objects during debugging.

[nyanshak]

I just tested this and now changes in the UI are reflected in terraform plan (reverting manual changes back to the expected state).

@radeksimko @grubernaut @stack72 I'd love to get this merged and tagged with a new version (0.1.1?). Pinging for review

[nyanshak]

@radeksimko @grubernaut @stack72

This is a hugely important bug-fix. Don't mean to be annoying, but can we get a review and either merge or some feedback on what needs to change?

As an aside, if this repo is not one that you're keen on maintaining (lack of visibility, don't use datadog, or lack of interest), I'd be willing to discuss getting additional people write access to this repo. If that's something that you're interested in, let me know.

[grubernaut]

Hey @nyanshak, sorry this hasn't been merged for you yet. Although @stack72 and myself are no longer employees at HashiCorp. @catsby, @tombuildsstuff, and @apparentlymart are though!

[nyanshak]

My bad! I was going based off most recently merged commits :'( Sorry

[apparentlymart]

Thanks for this @yfronto, @nyanshak!

Sorry for the delay in reviewing this. We're about to head into the next major release period and so we've been more heads-down than usual, unfortunately. 😖