When fetching the JSON from the ReviewRequest API using

GET review-requests/<id>/, the field issue_verifying_count is

missing and should be included.

Note that this field already exists in the review request model, and

counts issues which have the status VERIFYING_RESOLVED or

VERIFYING_DROPPED, and these issues are not included in the currently

displayed fields which are issue_dropped_count, issue_open_count

and issue_resolved_count.

With this fix, we display the field issue_verifying_count in the JSON.

Also, a unit test is included to assert that all four issue count fields

are visible.

User has a review with one open issue and one issue

awaiting verification.
Using httpie, run http :8080/api/review-requests/<id>/
Expected output contains:

        "issue_dropped_count": 0,
        "issue_open_count": 1,
        "issue_resolved_count": 0,
        "issue_verifying_count": 1,


Run the new unit test

./tests/runtests.py
    reviewboard.webapi.tests.test_review_request:
    ResourceItemTests.test_get_contains_all_issue_counts