Upgrade to Jupyter Notebook

* Change minimal-notebook to install notebook=4.0*
* Change other Dockerfile to point to 4.0 Docker Hub tag (to be built)
* Change config and pem file paths for jupyter
* Install ipywidgets in all containers that have a Python stack
* Update all READMEs to describe v3.2 and v4.0 since Docker Hub only shows one README for all tags

Contribution (c) Copyright IBM Corp. 2015

minimal-notebook/jupyter_notebook_config.py

@@ -0,0 +1,27 @@
+# Copyright (c) Jupyter Development Team.
+from jupyter_core.paths import jupyter_data_dir
+import subprocess
+import os
+
+PEM_FILE = os.path.join(jupyter_data_dir(), 'notebook.pem')
+
+c = get_config()
+c.NotebookApp.ip = os.getenv('INTERFACE', '') or '*'
+c.NotebookApp.port = int(os.getenv('PORT', '') or 8888)
+c.NotebookApp.open_browser = False
+
+# Set a certificate if USE_HTTPS is set to any value
+if 'USE_HTTPS' in os.environ:
+    if not os.path.isfile(PEM_FILE):
+        # Generate a certificate if one doesn't exist on disk
+        subprocess.check_call(['openssl', 'req', '-new', 
+            '-newkey', 'rsa:2048', '-days', '365', '-nodes', '-x509',
+            '-subj', '/C=XX/ST=XX/L=XX/O=generated/CN=generated',
+            '-keyout', PEM_FILE, '-out', PEM_FILE])
+    c.NotebookApp.certfile = PEM_FILE
+
+# Set a password if PASSWORD is set
+if 'PASSWORD' in os.environ:
+    from IPython.lib import passwd
+    c.NotebookApp.password = passwd(os.environ['PASSWORD'])
+    del os.environ['PASSWORD']