export application object when using gunicorn or wsgi, fix #20

For higher concurrency (if possible at all with SQLite), gevent will be used if
installed (`pip install gevent`). Furthermore, `weave-minimal` exports an
*application* object for uWSGI and Gunicorn, e.g.:

```bash
$ env ENABLE_REGISTRATION=1 DATA_DIR=/var/lib/... gunicorn weave -b localhost:1234
```

Do *not* use multiple processes to run `weave-minimal`. The code does not
acquire inter-process locks on the database and I have no plans to add a IPC
concurrency pattern to the rather simple code base (programmer's lame excuse,
I know).

README.md

@@ -28,9 +28,6 @@ parameters and a short description.
     $ weave-minimal --enable-registration
      * Running on http://127.0.0.1:8080/
 
-For high concurrency (if possible at all with SQLite), gevent will be used if
-installed (`pip install gevent`).
-
 To run weave-minimal as a daemon, consider this SysVinit script:
 
 ```bash
@@ -195,3 +192,19 @@ For nginx the code to add would be:
         ssl_ciphers HIGH:!aNULL:!MD5:RC4+RSA;
         # ...
     }
+
+Deployment
+----------
+
+For higher concurrency (if possible at all with SQLite), gevent will be used if
+installed (`pip install gevent`). Furthermore, `weave-minimal` exports an
+*application* object for uWSGI and Gunicorn, e.g.:
+
+```bash
+$ env ENABLE_REGISTRATION=1 DATA_DIR=/var/lib/... gunicorn weave -b localhost:1234
+```
+
+Do *not* use multiple processes to run `weave-minimal`. The code does not
+acquire inter-process locks on the database and I have no plans to add an IPC
+concurrency pattern to the rather simple code base (programmer's lame excuse,
+I know).

weave/__init__.py

@@ -181,13 +181,12 @@ def initialize(self, uid, password):
 
         print('[info] database for `%s` created at `%s`' % (uid, dbpath))
 
-
     def dispatch(self, request, start_response):
         adapter = url_map.bind_to_environ(request.environ)
         try:
             handler, values = adapter.match()
             return handler(self, request.environ, request, **values)
-        except NotFound as e:
+        except NotFound:
             return Response('Not Found', 404)
         except HTTPException as e:
             return e
@@ -270,3 +269,10 @@ def main():
         WSGIServer((options.host, options.port), app).serve_forever()
     except ImportError:
         run_simple(options.host, options.port, app, use_reloader=options.reloader, threaded=True)
+
+
+if sys.argv[0].endswith(("gunicorn", "uwsgi")):
+    application = make_app(
+        data_dir=os.environ.get("DATA_DIR", ".data/"),
+        base_url=os.environ.get("BASE_URL", None),
+        register=bool(os.environ.get("ENABLE_REGISTRATION", "0")))