Add directory src/main/resources and filtering to true

Add directory src/main/resources and filtering to true. This ensures
that e.g. {project.version} in resource files are replaced too. This is
mandatory to have the spring-devtools.properties updated with the kafka
version each time.

Resolves #240

kafka/pom.xml

@@ -100,6 +100,12 @@
     </dependencies>
 
     <build>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
         <plugins>
             <plugin>
                 <artifactId>maven-jar-plugin</artifactId>