Refactor the `stryker-cli` class

The stryker-cli is untestable at the moment. See https://github.com/stryker-mutator/stryker/blob/master/packages/stryker/src/stryker-cli.ts. Simply require-ing the file is enough to start mutation testing. I would rather see an implementation with a class.

So instead of require('../src/stryker-cli) in the stryker binary i would like to see something like const StrykerCli = require('../src/StrykerCli'); new StrykerCli(process.argv).run().

Next we should create some unit tests for the cli.

[simondel]

Hi! Thanks for wanting to contribute 😃 I think you’re trying to push to our repository. That is the output of the command git remote get-url origin is it this repository?

To contribute, you can fork this repository (top right of the github page). That creates a copy of stryker on your profile at https://github.com/bicep/stryker. You can then push to that repository can create a PR from there. You can use the command git remote set-url origin https://github.com/bicep/stryker to change the url of the remote named origin.

If you need any help. let us know! Also, have you signed up for hacktoberfest?

[simondel]

Fixed with #426 🎉