Code quality and style

[achilleas-k]

I intend to add automatic checks on pull requests for these, but for now, here's a list of some of the code style issues that need to be addressed:

• os.system() should never be used. All instances should be replaced by subprocess.call() or check_output().
• Indent Python code with 4 spaces (no tabs).
• Adhere to PEP8 strictly.
• Concatenate strings that represent filesystem paths using os.path.join().
• Commented out code should be removed, or if there's a good reason for it to remain, it shouldn't be a """string""" but a # comment.

[mrinalwahal]

Roger. I've set up pylint and pep8. Will follow this from now on. All instances of os.system() have been removed. You can test it now.

[achilleas-k]

Done.