Added pep8 tox environment
Clean-up command-line options

* The `options` should be used instead of the `addOptions`;
* Small help strings clean-up.
Merge pull request #37 from skudriashev/command-line-options

Clean-up command-line options
Merge pull request #34 from skudriashev/tox-pep8-env

Added pep8 tox environment
Use string format function in all cases
Merge pull request #38 from skudriashev/use-format

Use string format function in all cases