update some library's versions

Author: Kazuyuki Kohno

pom.xml

@@ -41,7 +41,7 @@
         <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-release-plugin</artifactId>
-         <version>2.1</version>
+         <version>2.5</version>
          <configuration>
            <mavenExecutorId>forked-path</mavenExecutorId>
          </configuration>
@@ -186,7 +186,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-source-plugin</artifactId>
-            <version>2.1.2</version>
+            <version>2.4</version>
             <executions>
               <execution>
                 <id>attach-sources</id>
@@ -199,7 +199,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-javadoc-plugin</artifactId>
-            <version>2.7</version>
+            <version>2.10.1</version>
             <executions>
               <execution>
                 <id>attach-javadocs</id>