* modernize js and use babel
- add babel toolchain to transform modern JS to ES5
- extend eslint config for modern rules
- fixes linting issues via `eslint --fix` and manual fixes
* run 'make css' to satisfy CI
* code style tweaks and set js indendation to 2 in .editorconfig
* regenerate js
* UI: Repo header tweaks
- Use basic buttons on the header buttons, matching gogs
- Make 'Manage topic' text smaller, remove margin-left with no topics
present
- Move various inline styles to CSS
- Use flexbox on header title and buttons
* fix indentation
* reverse media query wrapping
* fix inconsisten whitespace
