Bug 1030972 - Import tasks from Bugzilla

This is a post-merge cleanup of some of the code (pep8 stuff) and also addresses two issues:

1. The label for "Import task" has been changed to "Import tasks"
2. On the task detail page, if a Bug id exists in the task name it becomes linkified

Note that I am not sure of my solution to #2. I'm not sure if I should have put the code into the view, and also not sure of my use of `|safe` in the template, so I'd appreciate feedback on those.

Feels like this should be a helper like this
```
@register.filter
def buglinkify(obj):
    return jinja2.Markup(
        re.sub(
            r'(([Bb]ug )?(\d+))',
            r'<a href="https://bugzilla.mozilla.org/show_bug.cgi?id=\3">\1</a>',
            unicode(obj))
    )
```

and then you can {{ task.name|buglinkify }} and also use it in https://github.com/mozilla/oneanddone/blob/master/oneanddone/tasks/templates/tasks/confirmation.html#L35

BTW just a heads up to be twice as careful when using `Markup` or `safe`. In this case we're bringing in bug id from a trusted source which I think it's fine, but if we're to "safe" bug summary instead that could be problem.