Add an option to disable host blocking.

doc/help/settings.asciidoc

@@ -143,6 +143,7 @@
 |<<content-cookies-accept,cookies-accept>>|Whether to accept cookies.
 |<<content-cookies-store,cookies-store>>|Whether to store cookies.
 |<<content-host-block-lists,host-block-lists>>|List of URLs of lists which contain hosts to block.
+|<<content-host-blocking-enabled,host-blocking-enabled>>|Whether host blocking is enabled.
 |==============
 
 .Quick reference for section ``hints''
@@ -1235,6 +1236,17 @@ The file can be in one of the following formats:
 
 Default: +pass:[http://www.malwaredomainlist.com/hostslist/hosts.txt,http://someonewhocares.org/hosts/hosts,http://winhelp2002.mvps.org/hosts.zip,http://malwaredomains.lehigh.edu/files/justdomains.zip,http://pgl.yoyo.org/adservers/serverlist.php?hostformat=hosts&amp;mimetype=plaintext]+
 
+[[content-host-blocking-enabled]]
+=== host-blocking-enabled
+Whether host blocking is enabled.
+
+Valid values:
+
+ * +true+
+ * +false+
+
+Default: +pass:[true]+
+
 == hints
 Hinting settings.
 

qutebrowser/browser/network/networkmanager.py

@@ -326,13 +326,17 @@ class NetworkManager(QNetworkAccessManager):
         elif scheme in self._scheme_handlers:
             return self._scheme_handlers[scheme].createRequest(
                 op, req, outgoing_data)
+
+        host_blocker = objreg.get('host-blocker')
         if (op == QNetworkAccessManager.GetOperation and
-                req.url().host() in objreg.get('host-blocker').blocked_hosts):
+                req.url().host() in host_blocker.blocked_hosts and
+                config.get('content', 'host-blocking-enabled')):
             log.webview.info("Request to {} blocked by host blocker.".format(
                 req.url().host()))
             return networkreply.ErrorNetworkReply(
                 req, HOSTBLOCK_ERROR_STRING, QNetworkReply.ContentAccessDenied,
                 self)
+
         if config.get('network', 'do-not-track'):
             dnt = '1'.encode('ascii')
         else:

qutebrowser/config/configdata.py

@@ -622,6 +622,10 @@ DATA = collections.OrderedDict([
          "- One host per line\n"
          "- A zip-file of any of the above, with either only one file, or a "
          "file named 'hosts' (with any extension)."),
+
+        ('host-blocking-enabled',
+         SettingValue(typ.Bool(), 'true'),
+         "Whether host blocking is enabled."),
     )),
 
     ('hints', sect.KeyValue(