Execute and render ipynb's similar to spin R / Rmd scripts

@stefanches7 is already working on this.

Since Dec 6, 2019.

It would be nice to be able to specify a similar header in the jupyter notebook as in R. wBuild would then parse this configuration and run the notebook. The notebook can be parametrized and executed using the following code

```python
import subprocess
import os

def jupyter_nbconvert(input_ipynb):
""" .ipynb -> .html
"""
subprocess.call(["jupyter",
"nbconvert",
input_ipynb,
"--to", "html"])

def render_ipynb(template_ipynb, rendered_ipynb, params=dict()):
"""Render the ipython notebook
Args:
template_ipynb: template ipython notebook where one cell defines the following metadata:
{"tags": ["parameters"]}
render_ipynb: output ipython notebook path
params: parameters used to execute the ipython notebook
"""
import papermill as pm # Render the ipython notebook

os.makedirs(os.path.dirname(rendered_ipynb), exist_ok=True)
pm.execute_notebook(
template_ipynb, # input template
rendered_ipynb,
kernel_name="python3", # default kernel
parameters=params
)
jupyter_nbconvert(rendered_ipynb)

rule compile_notebook:
"""Run the notebook and convert it to html
"""
input:
example='example_file_{some_param}.csv',
ipynb = "src/.ipynb"
output:
ipynb = "output/.ipynb",
html = "output/.html"
run:
render_ipynb(input.ipynb, output.ipynb,
params=dict(example=input.example,
some_param=wildcards.some_param))
jupyter_nbconvert(output.ipynb)
```

## Required packages
- papermill: https://github.com/nteract/papermill

## Related
- https://bitbucket.org/snakemake/snakemake/issues/529/support-running-from-ipython-notebooks
- https://github.com/jmeppley/snakemake_magic/blob/master/prototype/notebooks/snakemake%20magic.ipynb