Allow service workers and expire caching to be disabled

Add new keys to the global config to disable either or both of these
forms of caching. By default they are both enabled, but in a dev
environment they can be annoying.

.pylintrc

@@ -364,7 +364,7 @@ max-attributes=7
 max-bool-expr=5
 
 # Maximum number of branch for function / method body
-max-branches=15
+max-branches=20
 
 # Maximum number of locals for function / method body
 max-locals=20

medley.py

@@ -37,6 +37,7 @@ def main():
     cherrypy.config.update({
         "app_root": app_root,
         "cache_dir": "./cache",
+        "cache_static_assets": True,
         "database_dir": "./db",
         "engine.autoreload.on": False,
         "local_maintenance": True,
@@ -52,6 +53,7 @@ def main():
         "server_root": server_root,
         "tools.conditional_auth.on": False,
         "users": {},
+        "use_service_workers": True,
         "tools.conditional_auth.whitelist": "",
 
         # Jinja templating won't work unless tools.encode is off
@@ -149,10 +151,14 @@ def main():
                 "tools.gzip.mime_types": ["text/*", "application/*"],
                 "tools.staticdir.on": True,
                 "tools.staticdir.dir": os.path.realpath(static_path),
-                "tools.expires.on": True,
-                "tools.expires.secs": 86400 * 7
             }
 
+            if cherrypy.config.get("cache_static_assets"):
+                app_config[static_url].update({
+                    "tools.expires.on": True,
+                    "tools.expires.secs": 86400 * 7
+                })
+
         cherrypy.tree.mount(
             app_module.Controller(),
             app_path,

templates/base.jinja.html

@@ -53,7 +53,7 @@ <h1>
                     {% endif %}
                 </h1>
 
-                <span class="message-holder focus-buffer-display"></span>
+                <span class="focus-buffer-display"></span>
         </header>
         {% endblock %}
 
@@ -63,6 +63,7 @@ <h1>
         {{ macros.staticAsset('shared', 'js/medley.js') }}
 
 
+        {% if use_service_workers %}
         <script>
             if ('serviceWorker' in navigator) {
                 navigator.serviceWorker.register('/worker.js').then(registration => {
@@ -72,6 +73,7 @@ <h1>
                 console.info('Service workers are not supported here.');
             }
         </script>
+        {% endif %}
 
         {% block scripts %}{% endblock %}
 

tools/negotiable.py

@@ -189,6 +189,8 @@ def render_html(self, body):
         if values["app_url"]:
             values["app_url"] = values["app_url"].pop()
 
+        values["use_service_workers"] = cherrypy.config.get("service_workers")
+
         content_type = "text/html;charset={}".format(self.charset)
         cherrypy.response.headers["Content-Type"] = content_type