Prepare for 7.0-1.21.0 release.

CHANGELOG.md

-# Changes in version 7.0-1.21.0 - 2019-1?-??
+# Changes in version 7.0-1.21.0 - 2019-10-18
 
  * Medium changes
+   - Add previously missing Jetty servlets dependency.
    - Fix a bug where old reverse DNS lookups were sometimes not
      cleared properly.
 

build.xml

@@ -11,7 +11,7 @@
   <property name="implementation-title" value="Onionoo" />
   <property name="onionoo.protocol.version" value="7.0"/>
   <property name="release.version"
-            value="${onionoo.protocol.version}-1.20.0-dev"/>
+            value="${onionoo.protocol.version}-1.21.0"/>
   <property name="metricslibversion" value="2.6.2"/>
   <property name="jetty.version" value="-9.2.21.v20170120" />
   <property name="warfile"