default view template shouldn't fail when assignee is nil
default view template shouldn't fail when assignee is nil

The default view template was failing with this error whenever I tried to
view a jira that had no assignee:
assignee: 2015-02-16T08:31:58.564-08:00 ERROR [util.go:109] Failed to execute template: template: template:7:20: executing "template" at <.fields.assignee.nam...>: nil pointer evaluating interface {}.name

mikepea/go-jira,garethbowles/go-jira