pywb 2.7.0 release

What's Changed

• New banner and calendar implementation in Vue.js, which supports localization/internationalization and easier local theming by @vanecat @ikreymer @tw4l with helpful feedback from @ldko
• New interactive timeline to assist in navigating between captures
• Add basic development Docker Compose configuration file
• Update documentation for new release (https://pywb.readthedocs.io/)
• Add contributing guide

Full Changelog: v-2.6.9...v-2.7.0