API tests

[MariusBaldovin]

Added tests for certificate endpoints:

• GET request: 200 (OK)
• POST request: 200 (OK), 400 (Bad Request), 409 (Already Exists)
• DELETE request: 200 (OK), 400 (Bad Request), 404(Not Found)

Added tests for report endpoints:

• GET request: 200 (OK), 404(Not Found)
• POST request: 200 (OK), 404(Not Found)
• DELETE request: 200 (OK), 400 (Bad Request), 404 (Not Found), 500 (Server Error)

Updated api.py:

• added 404 response in get_results if report is missing
• added 400 response in delete_report if timestamp format is incorrect

[jboddey]

You have a pylint issue to fix

[jboddey]

@MariusBaldovin 2 issues. 1) There are some tests in API that are failing 2) We need to figure out why the API tests say that it has passed even though tests have failed.

[MariusBaldovin]

@jboddey I will investigate this issue. In my dev branch, all the tests passed after the last commit.