Add pre push hook for linting and testing

[muralikrishna8]

We can add husky and add the hooks there https://www.npmjs.com/package/husky

[muralikrishna8]

For now added the pre-push hook for linting and testing.

Need to add the pre-commit hook for running the eslint --fix just for the changed files. That should:

• run eslint only for the staged files
• run eslint --fix

But for that we need to make some changes to the way we have our lint configured. Either we can find a way to do it with the gulp, or we can just use the eslint command directly without having the gulp task.

Closing this issue for now, and will work on the pre-commit hook as part of a #150