Fix complaints from pylint

Context

Since adding pylint and pep8 support to the test suite, it has shown up many inconsistent formatting errors, these need fixing.

Task Description

• Activate pep8 and pylint by default.
• Fix pep8 errors, with maxlinelength=119, ignoring:
  • E129: visually indented line with same indent as next logical line.
  • E125: continuation line with same indent as next logical line.
• Get a good pylint score (BuildStream standard).