Add pagination to jobs list

Hi,

I've added a paginator to the job listing, showing one hundred items per page, as this is the [Django's default](https://github.com/django/django/blob/1.6.5/django/contrib/admin/options.py#L377).

Seems there is some sort of confusion regarding the `0.7.0` tag and the `master` branch, as stated on #67, but looks like there is no other branch to pull. Anyway, I can send this again if you like.

Regards,
Tiago.
I think we can't use Django's builtin `Paginator` because it's designed to be used with querysets in mind. We should use `queue.get_jobs(offset=x, length=y)` instead.

I don't mind just having a simple scheme like "next" and "previous" either.