[RFC] Drop resource-level license detection issue reports in favour of codebase-level summary, with unique license detection issues

Presently with https://github.com/nexB/scancode-results-analyzer/pull/44, there are two attributes added,

```
codebase_attributes : "license_detection_issues_summary"

resource_attributes : "license_detection_issues"
```

where the `resource_attribute` represents a `file-view` [example](https://github.com/nexB/scancode-results-analyzer/blob/summary-plugin/tests/data/analyzer-plugins/results_analyzer_from_sample_json_expected_summary.json#L82), where every file has license detection issues potentially, and the
`codebase_attribute` is an `issue-view` [example](https://github.com/nexB/scancode-results-analyzer/blob/summary-plugin/tests/data/analyzer-plugins/results_analyzer_from_sample_json_expected_summary.json#L44), where we go through issues (unique issues, with all their occurances) one by one, instead of files.

The `issue-view` makes more sense in terms of review and resolving, and as @pombredanne suggests even dropping the `resource_attribute` entirely, and just have the `codebase_attribute` as an `issue-view`, makes sense.