Upgrade maven-javadoc-plugin to 3.0.0

This version seems to be much stricter and reports a lot more errors
in the javadoc formatting.

Disable failOnError to prevent the build from failing due to these
newly reported problems. These should be fixed in a follow-up commit.

Change-Id: Ia403cbedf72cfe8bdaf09f30e42e3bf96084ae52
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

pom.xml

@@ -210,7 +210,7 @@
     <httpcore-version>4.4.6</httpcore-version>
     <slf4j-version>1.7.2</slf4j-version>
     <log4j-version>1.2.15</log4j-version>
-    <maven-javadoc-plugin-version>2.10.4</maven-javadoc-plugin-version>
+    <maven-javadoc-plugin-version>3.0.0</maven-javadoc-plugin-version>
     <tycho-extras-version>1.0.0</tycho-extras-version>
     <gson-version>2.2.4</gson-version>
     <spotbugs-maven-plugin-version>3.1.0-RC8</spotbugs-maven-plugin-version>
@@ -737,6 +737,7 @@
             <artifactId>maven-javadoc-plugin</artifactId>
             <configuration>
               <additionalparam>-Xdoclint:-missing</additionalparam>
+              <failOnError>false</failOnError>
             </configuration>
           </plugin>
         </plugins>
@@ -748,6 +749,7 @@
             <artifactId>maven-javadoc-plugin</artifactId>
             <configuration>
               <additionalparam>-Xdoclint:-missing</additionalparam>
+              <failOnError>false</failOnError>
             </configuration>
           </plugin>
         </plugins>