Install Gatsby and basic plugin packages

References:

  (1) https://www.npmjs.com/package/gatsby
  (2) https://www.npmjs.com/package/gatsby-plugin-canonical-urls
  (3) https://www.npmjs.com/package/gatsby-plugin-catch-links
  (4) https://www.npmjs.com/package/gatsby-plugin-no-sourcemaps
  (5) https://www.npmjs.com/package/gatsby-plugin-react-helmet
  (6) https://www.npmjs.com/package/gatsby-source-filesystem
  (7) https://www.npmjs.com/package/gatsby-plugin-remove-trailing-slashes
  (8) https://www.npmjs.com/package/gatsby-transformer-yaml

GH-27