Add note about customizing the startup with before-notebook.d

Adding link to a new Community Stack : csharp-notebook

Adding link to a new Community Stack : csharp-notebook is a community Jupyter Docker Stack image. Try C# in Jupyter Notebooks.

Update tensorflow to 1.12

Remove apt-get clean command. Unecessary on official Ubuntu images.

Disable mounting of service account token under OpenShift.

notebook 5.7.2

updated the base image to ubuntu:18.04

Update scikit-learn to 0.20.*

Update JupyterLab and extensions to 0.35.4

Bumped Spark to 2.4.0 and miniconda to 4.5.11

Bumped Spark to 2.4.0

Update to official Toree 0.3.0-incubating release

[ci skip] Disable linkcheck

Fails too often on Travis

Adding recipe for nbextension spellchecker for issue 675

fix: #749; datascience-notebook: for julia 1.0, JULIA_PKGDIR is repla…