Fixes #21 Changes to automate error checking and improved code formmating.

Added a git hook, that fires before pushing to a remote. This hook runs the following checks

• check for uncommitted work, need to stash changes or commit before pushing
• yarn install --check-files make sure you have the right packages installed
• prettier . --write . auto-reformats code to match prettier rules
• eslint static error checks

All fixes have been tested and applied to the branch gh-21-linting-test. Take a look at that branch if you would like to review the end result.

Note you can always skip the check by adding the --no-verify option at the end of you push. Example git push origin my-feature-branch --no-verify