Bump notebook to 6.0.0, jupyterlab to 1.0.4, conda to 4.7.10

Inline PNG breaks sphinx gettext

Add java-notebook to the list of community stacks.

I modified 'docs/using/selecting.md' to include a link to the java-notebook project.

Added install of e1071 R package

conda 4.7.5

jupyterlab_bokeh@1.0.0 (rebase on PR #894) for JupyterLab 1.0.0

it makes the conda env invalid, which causes errors in later installs

Community haskell stack binder link

has fixed dependencies

much faster installs

had to move WORKDIR $HOME up due to tempfile permission issues with conda 4.7

Pin conda version to $CONDA_VERSION

Pin the conda version so that a call to `conda update --all` will not
cause conda to update itself to a higher version with possible breaking
changes.

Motivating example: Upgrade from __4.6.*__ to __4.7.5__ causes the build to fail
due to a conda error:

    [Errno 13] Permission denied: '/.cph_tmpilpdzq7x'

Resolves #891

Add binder link to Community Stack crosscompass/ihaskell-notebook.

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.