"Create Issue" button doesn't show up if user isn't logged in. github.com/shurcooL/issuesapp#40

This is what a logged in user sees:

A logged out user doesn't see the "Create Issue" button:

This is because the "create-issue" template currently displays the "Create Issue" button only if there's a logged in user:

https://github.com/shurcooL/issuesapp/blob/9e2c196c3359f4fbbf7e14b005ef54bcae83a768/assets/_data/issues.html.tmpl#L30

This is not ideal. What it should ideally be checking is whether the issue tracking service supports issues being created (most do). If so, the button should be displayed. Clicking it will give an unauthenticated response, which can be intercepted by redirecting to a login prompt, and then back to the new issue page.

There are some read-only service implementations, such as github.com/shurcooL/issues/maintner, used by golang.org/x/build/maintner/cmd/maintserve, that we shouldn't break while fixing this.

Resolved via https://github.com/shurcooL/issuesapp/commit/ea4a89bf5aa6ddc8199c3b9fc7c98ac5003bcdb5.