Move post history on sidebar

[treyhunner]

Convert that to a templatetag so we can just toss it in base.html and deal with settings from there.
Put num_display in settings? Make it part of the template tag? Even use a template tag?

@treyhunner and I talked about using a context middleware, but I'm kind of leery of middleware in general.

[treyhunner]

We've agreed that we should make a template tag that fetches the post history data from the database and includes our template file to render it.

[treyhunner]

Turned this into a pull request.

[alaindomissy]

The second sentence of this paragraph should be changed or removed:
For this workshop, a 1.6.x version is required. If instead you see a "No module named django" message, please follow the Django installation instructions.

@paulcollinsiii Sorry, I probably did not attach this comment to the right spot. This comment applies to a section of tutorial#1 that has not been changed since the first workshop. Because of the additional instructions about installing django 1.6 before creating a requirement.txt file, the link and suggestion to follow the Django installation instructions seem no longer needed.

[paulcollinsiii]

@alaindomissy does that comment apply to something in my PR? I'm not seeing that text but it's entirely possible I'm blind.

[treyhunner]

I think this should be "Template tags" or maybe "Custom template tags"

[treyhunner]

Uh oh... a link reference that doesn't go anywhere.

[treyhunner]

I've made a lot of changes to this documentation.

I would like some feedback/help on what we have so far.

A rendered version can be found here: http://test-driven-django-development.readthedocs.org/en/issue-10/07-templatetags.html

[willingc]

Perhaps add this between the two sentences in this paragraph...

DRY or "Don't Repeat Yourself" is a rule of thumb for good programming practice. http://programmer.97things.oreilly.com/wiki/index.php/Don%27t_Repeat_Yourself

[willingc]

Replace "means that" with "enables"