added simple example using flask (#1140)

added simple example using flask

Author: ocefpaf

docs/flask.rst

@@ -0,0 +1,9 @@
+Using folium with flask
+=======================
+
+A very common use case is to use folium with in a flask app.
+The trick is to return folium's HTML representation.
+Here is an example on how to d that:
+
+
+.. literalinclude:: ../examples/flask_example.py

docs/index.rst

@@ -33,5 +33,6 @@ Contents
 
    installing
    quickstart.ipynb
+   flask
    modules
    plugins

examples/flask_example.py

@@ -0,0 +1,32 @@
+""" flask_example.py
+
+    Required packages:
+    - flask
+    - folium
+
+    Usage:
+
+    Start the flask server by running:
+
+        $ python flask_example.py
+
+    And then head to http://127.0.0.1:5000/ in your browser to see the map displayed
+
+"""
+
+from flask import Flask
+
+import folium
+
+app = Flask(__name__)
+
+
+@app.route('/')
+def index():
+    start_coords = (46.9540700, 142.7360300)
+    folium_map = folium.Map(location=start_coords, zoom_start=14)
+    return folium_map._repr_html_()
+
+
+if __name__ == '__main__':
+    app.run(debug=True)