Link to last issue broken

[hectorsector]

The link to the final issue in my PR was broken. It may be easiest to get the final issue's URL after the createIssue action that creates it, and then pass that URL to the respond action. This is also safer if the learner has opened extra issues (and so the final issue won't be the number we expect).

[leostera]

Should be fixed in 37c5abf