The following changes have been made.

- `base-notebook`
  - `Changed`: Bump Ubuntu
  - `Changed`: Bump conda
  - `Fixed`: Add missing `apt-get clean`
- `minimal-notebook`
  - `Removed`: `jed` editor see #1174 (partial)
  - `Deprecated`: `emacs` editor (in the documentation and in the image) see #1174 (partial)
- `scipy-notebook`
  - `Fixed`: Add missing `apt-get clean`
  - `Changed`: Bump `dask`
  - `Changed`: Bump `protobuf`
- `r-notebook`
  - `Changed`: Bump `r-base`
  - `Changed`: Bump `r-rmarkdown`
  - `Removed`: The description of `tidyverse` packages because it's not the place to do that and it will always be obsolete.
- `datascience-notebook`
  - `Changed`: Bump `r-base` to `4.0.x` see #1102 (partial)
  - `Removed`: `plyr` package because it's retired fixes #1103
  - `Removed`: `r-reshape2` package because it's retired fixes #1103
  - `Changed`: Bump `r-rmarkdown`
  - `Changed`: Bump Julia
- `tensorflow-notebook`
  - `Changed`: Bump `tensorflow`
- `pyspark-notebook`
  - `Fixed`: Add missing `apt-get clean`
  - `Changed`: Bump `pyarrow`
- `all-spark-notebook`
  - `Fixed`: Add missing `apt-get clean`
  - `Changed`: Bump `r-base` to `4.0.x` see #1102 (partial)
  - `Changed`: Bump `r-sparklyr`