Add Vert.x proxy code generation setup to pom

[toniedzwiedz]

Proxies for any custom knots will require auomatic code generation by Vert.x

<executions>
            <execution>
              <id>default-compile</id>
              <configuration>
                <annotationProcessors>
                  <annotationProcessor>io.vertx.codegen.CodeGenProcessor</annotationProcessor>
                </annotationProcessors>
                <generatedSourcesDirectory>${generated.dir}</generatedSourcesDirectory>
                <compilerArgs>
                  <arg>-AoutputDirectory=${project.basedir}/src/main</arg>
                </compilerArgs>
              </configuration>
            </execution>
            <execution>
              <id>default-testCompile</id>
              <configuration>
                <annotationProcessors>
                  <annotationProcessor>io.vertx.codegen.CodeGenProcessor</annotationProcessor>
                </annotationProcessors>
                <generatedTestSourcesDirectory>${generated.dir}</generatedTestSourcesDirectory>
                <compilerArgs>
                  <arg>-AoutputDirectory=${project.basedir}/src/test</arg>
                </compilerArgs>
              </configuration>
            </execution>
          </executions>