Resolve unmet peer dependencies

[masiuchi]

Some warnings are displayed when executing "yarn install".

$ yarn install
yarn install v1.22.22
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
warning " > eslint-config-airbnb@13.0.0" has unmet peer dependency "eslint-plugin-jsx-a11y@^2.2.3".
warning " > eslint-config-airbnb@13.0.0" has unmet peer dependency "eslint-plugin-react@^6.6.0".
[4/4] Building fresh packages...
success Saved lockfile.
Done in 3.16s.

This pull request resolves the warnings by installing missing modules.

[masiuchi]

force-pushed to fix the previous wrong changes

[masiuchi]

Sorry, I noticed that eslint-config-airbnb is not used. So I will close this pull request and add the deletion process to #22.