template-v0.2.0

• Use Gravatar for user profile picture.
• AB#21: Migrate to CoreUI-vue v3.1.1.
• AB#22: Integrate with Exter.
• AB#25: Use JWT as login-token.
• EP#25: Rebuild sample app.
• Others:
  • Vuejs: replace data with computed (https://techformist.com/data-vs-computed-vs-watcher-in-vue-components/) if possible.
  • Other fixes and enhancements.