* [docs] Crafting a new release

* Separate RC from VERSION

* Fix pypi_push.sh and refine instructions

* Add SUPERSET_ prefix to env variables

* Finalize release instructions

* Change one-off to First Time Only

* Add tagging of final version

* Convert some remaining env variables and add a check step to pypi deploy

* Refine release instructions

* Add version to svn message

Also documenting this step under RELEASING/README.md

Turns out since we use `git archive`, there's no need for `git clean`
which was pretty disruptive.

* [WiP] Improvements related to ASF release process

* Removing translation binaries (.mo)
* Working on 2 docker files to help package and validate releases
  * Dockerfile.from_tarball: takes a VERSION as input, downloads
    official source release fro svn and bakes it into a functional
    docker image that can be validated
  * Dockerfile.make_tarball: helps a maintainer to package and sign a
    release candidate or release

* Address COPYRIGHT + LICENSE issues

(cherry picked from commit 5ae2836b)

* Add Roboto font to LICENSE, remove glyphicons files

(cherry picked from commit 9615f39f7a556afe217b4e3288c9116f8ffaab91)

* remove unused LICENSE entries

* Change babytux to open image in birth dashboard

(cherry picked from commit 2776d11893596a029b8af37b96fd6ce1a9f12059)

* Improve instructions

* Docker tweaks

(cherry picked from commit df6e6462458ea8cff1482c142921b20f5607ad8e)

* Include image

* [docs] improve the RELEASING.md docs

* more tweaks

* Apache Releases

https://github.com/mistercrunch/superset/blob/apache-releases/RELEASING.md#apache-releases

* npm run prod -> npm run build

* Download RAT binary via HTTPS, not HTTP

* Merge branch 'patch-1' of github.com:hajdbo/incubator-superset into patch-1

* Add licenses

* More licenses

* Ignore messages.json as they are generated

* More licenses

* Also typescript

* Fix alignment

* Add to svg

* Many more licenses

* more licenses

* Better excludes

* Add licenses to docs and md files

* Pre-finalize licenses

* Fix newlines

* Finalize all sourde licenses

* Fix lint

- Reorganize sections for better navigability
- Add table of contents
- Rework frontend assets section for clarity and DRY
- Rework translating section for clarity, add "Add Translations" contribution type
- Move release docs only useful for maintainers to RELEASING.md
- Other miscellaneous improvements