Add wsgi.py to frontends. Update docs.

Author: rouilj

doc/installation.txt

@@ -950,8 +950,8 @@ uses a front end web server like nginx, hiawatha, apache configured as
 a reverse proxy. See your web server's documentation on how to set it
 up as a reverse proxy.
 
-The file wsgi.py should be in the current directory with the
-contents::
+The file wsgi.py (obtained from ``frontends/wsgi.py``) should be in
+the current directory with the contents::
 
   # if roundup is not installed on the default PYTHONPATH
   # set it here with:

frontends/README.txt

@@ -3,6 +3,9 @@ This directory contains alternate front-ends for Roundup.
 roundup.cgi
    This is a cgi-bin script.
 
+wsgi.py
+   This is a wrapper to be used when running under wsgi.
+
 ZRoundup
    This is a simple Zope frontend that installs as a regular Zope product.
 

frontends/wsgi.py

@@ -0,0 +1,16 @@
+# If you installed roundup to the system locations
+# using pip you don't need to change this
+# section. If you installed roundup in a custom
+# location, uncomment these lines and change the
+# path in the append() method to your custom path.
+#import sys
+#sys.path.append('/custom/location/where/roundup/is/installed')
+
+# Obtain the WSGI request dispatcher
+from roundup.cgi.wsgi_handler import RequestDispatcher
+
+# Set the path to tracker home.
+tracker_home = '/path/to/tracker'
+
+# Definition signature for app: app(environ, start_response):
+app =  RequestDispatcher(tracker_home)