Add tox.ini

[ManthanKeim]

tox.ini explains how to set up coala in tox properly.

Closes #344

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[palash25]

@ManthanKeim just one suggestion never make a PR from your master, always checkout a new branch from the master for a particular issue and keep your master clean.

We can overlook this mistake for now but you should keep this best practice in mind so that you are able to work on multiple PRs simultaneously in the future 😉

[ManthanKeim]

@palash25 thanks for the suggestion. I will surely consider that for future PRs.

[jayvdb]

@ManthanKeim , this task is to create documentation about tox.ini, not add a tox.ini to this repo.

[ananyaarun]

@ManthanKeim , Kindly read this https://api.coala.io/en/latest/Developers/Newcomers_Guide.html#step-3-creating-a-fork-and-testing-your-changes , These are some reasons why I would suggest you to not make PR's from master branch itself.
Also, Change your commit from "add" to "create"
else this Looks good to me :)