(PUP-1407) add required authorityKeyIdentifier extension to CRL

as pointed out in the PUP-1407 issue, currently the CA does not conform to RFC 5280 since it does not add the required authorityKeyIdentifier extension. This causes the CRL to not be able to be parsed properly by strict applications.
This request adds the extension to the CRL when it's generated as well as creates a test case for it.
In order to properly test it, I had to rewrite the test case to not just mock the OpenSSL classes but instead use a temporary CA (basically like other SSL test cases do)