Update TravisCI with new Django versions. Drop Lettuce to get builds working. Remove fixed Django requirement.
Requirements - don't pin fixed MPTT version, don't pin django-model-utils for tests, prep for future Armstrong.Dev
Updates to `.gitignore`
Readme - bump copyright date, Readme updates, fix package name, simplify install instructions, add neglected third settings parameter.
Drop Lettuce tests
Tests - cleanup imports
Tests - use `self.settings` to be more Django-like (`ArmSectionsTestCase` backported it from Django 1.4)
Tests - user `override_settings` instead to avoid so much indentation. PEP8
Tests - PEP8; use more appropriate `asserts`
Remove incorrect namespacing.
Documentation - remove Sphinx docs and update Readme.

The Sphinx docs are out of date, a maintenance headache and Armstrong just isn't using them.
The Readme gets new content and uses the new "contributing" section text.
PEP8 reformatting
Fix and properly deprecate the older ItemFilter `find_related_models` method.

The way it was coded with the `ItemFilter()` instantiation would never have worked. The setting is supposed to be a class which `get_backend()` instantiates.
update migration to the output from a newer South (0.8.4)

There's nothing here that changes our practice as South supports Django 1.2+. Unicode can't hurt and `db_index` on SlugField has been implied since Django 1.2 (maybe earlier).
use future/now-current version of `{% url %}` in template
Deprecate the `SectionTreeAdminMixin`. It's better `mptt` practice to use TreeForeignKey/TreeOneToOneField/TreeManyToManyField explicitly in the model definition.

- I don't believe we've ever used this in Armstrong itself so I don't think there is anything else to change.
- drop EMPTY_LABEL. It doesn't appear necessary.
- Fix: using EMPTY_LABEL in `formfield_for_manytomany()` was actually breaking
development env - fix static files use in newer Django's and provide required `STATIC_ROOT` setting. Drop Sites. Add some "no covers" for Coverage.
Coverage - increased to 100%. Fix duplicate test case name.
Merge branch 'v1.6.0-prep'