Add better error handling

[hassankhan]

Description

What is the use case that should be solved?

Currently, when the package throws an error, we see a full stack trace:

<PATH_TO_PROJECT>/git-author-check/dist/validateAuthor.js:16
        throw new Error(chalk_1.default.red(message));
        ^

Error: Invalid author email domain! Check that your config contains a definition for your domain.
    at Object.exports.default (<PATH_TO_PROJECT>/git-author-check/dist/validateAuthor.js:16:15)
    at run (<PATH_TO_PROJECT>/git-author-check/dist/index.js:12:29)
    at Object.<anonymous> (<PATH_TO_PROJECT>/git-author-check/dist/index.js:14:1)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Function.Module.runMain (module.js:693:10)
    at startup (bootstrap_node.js:191:16)

We should only show error messages in the console output.

Additional Data

Version of git-author-check you're using: 1.0.1

Node Version: 8.11

Operating System: macOS 10.13