Fix and update org token

[dloucasfx]

This PR fixes the dpm_limits , which a single line fix; but fixing this and/or running the existing test TestAccCreateUpdateOrgToken will fail with a server side error:

"code" : 500,
  "message" : "Server error occurred. Unique error identifier [24df50a1-e751-4a42-9adb-8eb759e875b9]"

This error is returned when the provider attempts to update an org token with a DPM/Category limit and not setting the authScopes in its payload.

In this PR I added auth_scopes to the token schema and I made it optional to keep it backward compatible;
Note, when you create a token, the server defaults to setting the value to ["API", "INGEST"] so the initial creation succeeds whether you set authScopes or not; but due to the TF SDK not supporting Default for complex types , in this case TypeList, I opted to set Computed to true; this will prevent false positive plan diffs .

I also added new test.

NOTE: Do Not Merge as this depends on this PR signalfx/signalfx-go#146 , once the it's merged, I need to update this PR to pull the new version of signalfx-go

update: signalfx-go is updated

Signed-off-by: Dani Louca dlouca@splunk.com

[keitwb]

Ok looks good.