Partial merge of #116 from 'garbas/pep8^'.

This merges everything but the last commit, which contains controversal
changes: https://github.com/NixOS/nixops/pull/116#issuecomment-20812087

Conflicts:
	coverage-tests.py
	nixops/backends/__init__.py
	nixops/backends/ec2.py
	nixops/backends/virtualbox.py
	nixops/deployment.py
	nixops/parallel.py
	nixops/resources/__init__.py
	nixops/resources/ec2_keypair.py
	nixops/resources/iam_role.py
	nixops/resources/s3_bucket.py
	setup.py
	tests.py
	tests/functional/test_encrypted_links.py