Feature Request: Include Roster Identifier in output of `accepted-assignments`

[kleinernik]

I would be helpful to include the Roster Identifier in output of accepted-assignments. For now it only includes the GitHub-username under the column student (which maybe also should be named GitHub-username?).

[shanep]

A recent update added the AssignmentGrade struct that contained the roster identifier of a student. It would be super helpful if the Student struct also had this field as shown below. That would enable this feature to be completed and several other cool features to be done :)

type Student struct {
    Id        int    `json:"id"`
    Login     string `json:"login"`
        RosterIdentifier      string `json:"roster_identifier"`
    AvatarUrl string `json:"avatar_url"`
    HtmlUrl   string `json:"html_url"`
}

[shanep]

Waiting on issue #48