Remove unnecessary use of exec plugin

Author: oschwald

pom.xml

@@ -232,24 +232,6 @@
                     <check />
                 </configuration>
             </plugin>
-            <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>exec-maven-plugin</artifactId>
-                <version>1.6.0</version>
-                <executions>
-                    <execution>
-                        <phase>initialize</phase>
-                        <id>invoke build</id>
-                        <goals>
-                            <goal>exec</goal>
-                        </goals>
-                    </execution>
-                </executions>
-                <configuration>
-                    <executable>git</executable>
-                    <commandlineArgs>submodule update --init --recursive</commandlineArgs>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>versions-maven-plugin</artifactId>