Fix maven warnings about missing plugin versions (#331)

This change updates the main pom file to include versions for the
maven plugins "sources", "javadoc" and "resources" in order to fix
a maven build warning.

Signed-off-by: Jens Reimann <jreimann@redhat.com>

Author: ctron

pom.xml

@@ -94,6 +94,21 @@
 						<target>${java.version}</target>
 					</configuration>
 				</plugin>
+				<plugin>
+					<groupId>org.apache.maven.plugins</groupId>
+					<artifactId>maven-javadoc-plugin</artifactId>
+					<version>2.9.1</version>
+				</plugin>
+				<plugin>
+					<groupId>org.apache.maven.plugins</groupId>
+					<artifactId>maven-resources-plugin</artifactId>
+					<version>2.4.2</version>
+				</plugin>
+				<plugin>
+					<groupId>org.apache.maven.plugins</groupId>
+					<artifactId>maven-source-plugin</artifactId>
+					<version>3.0.1</version>
+				</plugin>
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-deploy-plugin</artifactId>