Add simple issue / request system for info desk

[MarkusH]

In addition to #188 a simple issue / request system is helpful which allows people at the information desk to take some notes and leave them for later volunteers.

The form should be included on the detail view of #188 and contain only the textarea for the text field plus the submit button.

The current idea is rather simple:

class Comment(models.Model):
    profile = models.ForeignKey('accounts.Profile')
    author = models.ForeignKey('auth.User')
    text = models.TextField()
    posted = models.DateTimeField(auto_add_now=True)

    class Meta:
        ordering = ('-posted',)

[DasIch]

Just talked to Veit regarding giving out badges, replacing wrong ones etc. which he would like to log, using this system. Given that we won't be able to implement an issue system until the conference I would suggest having a text area for each ticket, that can be used for notes.

[MarkusH]

We have a different process implemented that doesn't require the website.