Completed task: "Update Issues for Repository route to get all issue data".

This pull request addresses the following issue:

* #80: Update Issues for Repository route to get all issue data

The `/api/issues` endpoint will now return the list of **all** issues (excluding pull requests) in a repository largely thanks to @drksephy's implementation of asynchronous requests (#69).

In addition, the `/#/issues` route will now display the following:

* Issue number
* Issue title (and link to respective issue page on GitHub)
* Issue state (open, closed)
* Issue creator (and link to respective issue creator's profile)
* Issue assignee (and link to respective issue assignee's profile)