Bug 971965 app for generating api tokens

@AdrianGaudebert or @rhelmer r?
At least I want both of your attention. 

With this patch, I have switched on `USE_TZ = True` in settings. That means that we're going **timezone aware** on ALL datetimes everywhere. 

For example, if you have:
```python
class SomeFOrm(django.forms.Form):
     d = django.forms.DateTimeField()
```
and you send this `?d=2012-01-01` and then do:
```python
if form.is_valid():
    print form.cleaned_data['d'].isoformat()
```
...it will now spit out: `'2012-01-01T00:00:00+00:00'`.

This patch introduces our first actual Django model that we've written. 
I chose not to use the middleware because it's not important enough to be there. And it doesn't have anything to do with any other Socorro data. With it being in Django it means I can tie it together with the django `User` and `Permission` models. 

I'll try to point out some important aspects within the code. 

![screenshot of the new page](https://f.cloud.github.com/assets/26739/2162260/2dd64cf6-94d0-11e3-9cfe-bd801616c9a4.png)

NB: There is no way to get to this page other than typing in "/api/tokens/" in the address bar. I think enabling this can be a later step when we know it works and can actually be used for something (e.g. [967555](https://bugzilla.mozilla.org/show_bug.cgi?id=967555))