PR #6 test refactoring. Squashes the `tests_take2` branch for merging.
Resolves #6 but since there were merge conflicts we'll put this up for review as well.

Merge tests_take2_squashed:
  PR #6 test refactoring. Squashes the `tests_take2` branch for merging.

Conflicts:
	armstrong/core/arm_layout/tests/_utils.py
	armstrong/core/arm_layout/tests/templatetags/layout_helpers.py
Removing Lettuce to get builds working again.
Merge pull request #10 from joncotton/master

Squash and resolve merge conflicts for "Take 2 - refactoring tests" PR #6