Revert "Merge branch 'clean-ipynb' into testing"

This reverts commit 004b052, reversing
changes made to 8ed91d8.

docs/CONTRIBUTING.md → CONTRIBUTING.md

@@ -30,42 +30,6 @@ Pushing to master is protected, you can only push heads that have an "green" sta
 
 If something goes wrong, `git reset --hard master origin/master` and try again.
 
-## Committing Jupyter Notebooks
-
-Our Jupyter Notebooks should be committed without their output cells and execution counts since generated output of
-probalistic methods makes version control unneccessarily complicated. The script <ipynb_drop_output.py> makes output
-stripping easy, but requires some preparation:
-
-### Preparation for each contributor machine
-
-Every contributor should:
-
-1. place the <ipynb_drop_output.py> script somewhere on the `$PATH`
-2. make it executable (`chmod a+x ipynb_drop_output.py`)
-3. configure a git filter called `clean_ipynb` as follows:
-
-```bash
-git config --global filter.clean_ipynb.clean ipynb_drop_output.py
-git config --global filter.clean_ipynb.smudge cat
-```
-
-This will edit your `~/.gitconfig` so you globally have this filter available. The filter is linked to notebooks using
-an entry in the `.gitattributes` file, this is already configured for this project.
-
-### Preparation of each notebook
-
-Each notebook needs a metadata entry to enable the filter. Open the notebook in Jupyter, click _Edit / Edit Notebook Metadata_
-and add the following entry to the outermost dictionary:
-
-```json
-  "git": {
-    "suppress_outputs": true
-  },
-```
-
-Now, when you add this notebook to the index or try to run a diff on it, the script is used to prepare a clean version.
-Your working copy will not be modified, so _you_ will see the output cells and execution counts you generated.
-
 ## Documentation
 
 The documentation is built using [Sphinx](http://www.sphinx-doc.org/).