Format hook

[kepta]

This PR adds the following dev dependency

• prettier
• precommit hook

The way it works is.

1. The user does some changes.
2. when he/she does git commit -m "my fix".
3. A precommit hook (prettier-eslint --write) runs.
4. It formats the code according the .eslintrc file.
5. Everything happens automagically.

cc @bkowshik @amishas157 @geohacker . Once the PR is merged I can format the entire code base to conform to the .eslintrc file.

(fixes #152 )

[bkowshik]

Good idea @kepta Curious to see what this does, I tried the following.

# 1. Pull in new changes for the branch.
git pull
git checkout format-hook

# 2. Change indentation for one compare function from 2 spaces to 4 spaces.
...

# 3. Add the file and commit it.
git commit -m 'Formatting by 4 spaces'
[format-hook c9b87db] Formatting by 4 spaces
 1 file changed, 25 insertions(+), 25 deletions(-)
 rewrite comparators/disputed_border_tag_changed.js (79%)

I was expecting the file to indent back to 2 spaces automatically.

[kepta]

@bkowshik you are saying it did not indent it back to 2 spaces?

[bkowshik]

Yes @kepta. Can you share an example of the hook in action?