Revert "Remove flask app"

This reverts commit e5beed9.

Procfile

@@ -0,0 +1 @@
+web: make && gunicorn app:app --log-file -

app.py

@@ -0,0 +1,27 @@
+"""
+This is a simple cheatsheet webapp.
+"""
+import os
+
+from flask import Flask, send_from_directory
+from flask_sslify import SSLify
+
+DIR = os.path.dirname(os.path.realpath(__file__))
+ROOT = os.path.join(DIR, 'docs', '_build', 'html')
+
+app = Flask(__name__)
+if 'DYNO' in os.environ:
+        sslify = SSLify(app)
+
+@app.route('/<path:path>')
+def static_proxy(path):
+    """Static files proxy"""
+    return send_from_directory(ROOT, path)
+
+@app.route('/')
+def index_redirection():
+    """Redirecting index file"""
+    return send_from_directory(ROOT, 'index.html')
+
+if __name__ == "__main__":
+    app.run(debug=True)