generate UMD version in dist directory on post install

[dotnetCarpenter]

[1.1.0] - 2017-12-31

Added

• Npm post-install hook now creates a dist/ directory with traits.js and
  traits.min.js. This allow for using the minified version through https://unpkg.com.
• Added changelog.
• Mention unpkg.com include option and fixed some formatting errors in markdown files.

Changed

• Npm main file no longer points to src/traits.js but to dist/traits.js. Since this is the
  unminified version, your module bundler can optimize the minification process according to your project.
• Updated dev dependencies. - qunit can not be updated to any version higher than 2.4.1 due to karma-qunit.

Removed

• Nodejs and Commonjs detection in traits.js.