The e1071 R package is a dependency of functions within the caret package. Without it, `caret::train` (for example) cannot be run. This pull request addresses issue #889 (https://github.com/jupyter/docker-stacks/issues/889). 

note - I first tried installing e1071 in the RUN command started on line 27 but that resulted in e1071 not installing (don't know why) but adding an additional RUN command led to succesful installation... So I just went with it.

Add `Specific Docker Image Options` for jupyter spark

Apply additional tags to base-notebook

* python-<version>
* notebook-<version>
* lab-<version>
* hub-<version>

jupyterhub 1.0

Update to Spark 2.4.3

Update RTD config file to v2

Community Stacks documentation ihaskell-notebook

Add ihaskell-notebook to the list of Community Stacks.

Changed `conda clean` flags to `--all -f -y`

Resolved conflicts between local branch and updates to the upstream
master.

More translation fixes

* msgstr fields should be empty
* File extension should be .po

Do not trigger another docs/local/en update and push
to master when localized text changes

Need to check file changes in TRAVIS_COMMIT_RANGE

Draft pages about translation

Setup travis en template update

[Doc] Change Spark Python Notebook entry point sentence