Replaced command-line uwsgi wrapper in the backend.http docs with gunicorn

gunicorn makes it easier to set up a uWSGI wrapper
around the web application, and it's easier to
install and document than handling uwsgi as an
external system dependency.

platypush/backend/http/__init__.py

@@ -155,19 +155,20 @@ class HttpBackend(Backend):
         * **bcrypt** (``pip install bcrypt``)
         * **magic** (``pip install python-magic``), optional, for MIME type
             support if you want to enable media streaming
-        * **uwsgi** (``pip install uwsgi`` plus uwsgi server installed on your
+        * **gunicorn** (``pip install gunicorn``) - optional but recommended.
-            system if required) - optional but recommended. By default the
-            Platypush web server will run in a process spawned on the fly by
-            the HTTP backend. However, being a Flask app, it will serve clients
-            in a single thread and won't support many features of a full-blown
-            web server.
 
-    Base command to run the web server over uwsgi::
+    By default the Platypush web server will run in a
+    process spawned on the fly by the HTTP backend. However, being a
+    Flask app, it will serve clients in a single thread and it won't
+    support many features of a full-blown web server. gunicorn allows
+    you to easily spawn the web server in a uWSGI wrapper, separate
+    from the main Platypush daemon, and the uWSGI layer can be easily
+    exposed over an nginx/lighttpd web server.
 
-        uwsgi --http :8008 --module platypush.backend.http.uwsgi --master --processes 4 --threads 4
+    Command to run the web server over a gunicorn uWSGI wrapper::
+
+        gunicorn -w <n_workers> -b <bind_address>:8008 platypush.backend.http.uwsgi
 
-    Bear in mind that the main webapp is defined in ``platypush.backend.http.app:application``
-    and the WSGI startup script is stored under ``platypush/backend/http/uwsgi.py``.
     """
 
     _DEFAULT_HTTP_PORT = 8008

platypush/backend/http/manifest.yaml

@@ -5,5 +5,6 @@ manifest:
     - flask
     - bcrypt
     - python-magic
+    - gunicorn
   package: platypush.backend.http
   type: backend

setup.py

@@ -78,9 +78,7 @@ setup(
         # Support for Pushbullet backend and plugin
         'pushbullet': ['pushbullet.py @ https://github.com/rbrcsk/pushbullet.py/tarball/master'],
         # Support for HTTP backend
-        'http': ['flask', 'bcrypt', 'python-magic'],
+        'http': ['flask', 'bcrypt', 'python-magic', 'gunicorn'],
-        # Support for uWSGI HTTP backend
-        'uwsgi': ['flask', 'uwsgi', 'bcrypt', 'python-magic'],
         # Support for MQTT backends
         'mqtt': ['paho-mqtt'],
         # Support for RSS feeds parser