PEP8 Indentation, lines and spacing.

Fix [PEP8](http://www.python.org/dev/peps/pep-0008/) indentation.

- 2 spaces -> 4 spaces (http://www.python.org/dev/peps/pep-0008/#indentation)
- Hanging indents ((http://www.python.org/dev/peps/pep-0008/#indentation))
- Fix ``ENOENT`` -> ``errno.ENOENT``.
- Spaces in between operators (0 space -> 1 space)
- Spaces in arguments (1 space to no space)
- Whitespace after ':'
- 2 lines between classes
- 1 line between methods
- One line expressions -> new line + indent inner code.