Various cleanups

Since the tests currently are failing I've cleaned up the package a little bit.

- Declare dependencies, cleanup (zcml, indenting, pep8, pyflakes)
- Remove z3c.autoinclude includeDependencies
- Replace tests with p.a.testing / ftw.testbrowser tests
- Use browserlayer for viewlet
- Remove no longer used utility.

@Tschanzt can you take a look? This should fix the broken tests.