Improve code heath of worst offenders

- Change triple quoted comments to plain comments.
- Change string formatting to argument in the logging commands.
- Comment out unused import.
- Rename variable that clashes with built-in.
- Tidy some white space.
Correct arguments to logging functions

- Unpack tuples when passed to logging functions as they should just be a
  series of arguments.
Improve code health of medium offenders

- Change string formatting to argument in the logging commands.
- Remove unused imports.
- Tidy some white space.
- Change 'not x is y' tests to 'x is not y'.
Improve code health

- Change string formatting to arguments in logging commands as this is how
  they should be called.
- Tidy some whitespace.
- Sort out some ambiguous indentation.
- Remove unused import.
- Compact some lone lines.
- Correct 'not x in y' to 'x not in y'.
Change comparisons to None to 'if cond is None:'
Correct two logging calls
Merge pull request #50 from apel/code_health

Improve code health