Update protocol version to 5.1.

CHANGELOG.md

+# Changes in version 5.1-1.??.? - 2018-??-??
+
+ * Medium changes
+   - Stop omitting "n" in summary docs for "Unnamed" relays/bridges.
+
+
 # Changes in version 5.0-1.10.1 - 2018-02-07
 
  * Medium changes

build.xml

@@ -8,7 +8,7 @@
 
   <property name="javadoc-title" value="Onionoo API Documentation"/>
   <property name="implementation-title" value="Onionoo" />
-  <property name="onionoo.protocol.version" value="5.0"/>
+  <property name="onionoo.protocol.version" value="5.1"/>
   <property name="release.version"
             value="${onionoo.protocol.version}-1.10.1-dev"/>
   <property name="metricslibversion" value="2.1.1"/>

src/main/java/org/torproject/onionoo/server/ResponseBuilder.java

@@ -123,7 +123,7 @@ public class ResponseBuilder {
     return this.charsWritten;
   }
 
-  private static final String PROTOCOL_VERSION = "5.0";
+  private static final String PROTOCOL_VERSION = "5.1";
 
   private static final String NEXT_MAJOR_VERSION_SCHEDULED = null;