Maven plugin updates.

pom.xml

@@ -86,7 +86,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.3</version>
+        <version>3.6.1</version>
         <configuration>
           <source>1.6</source>
           <target>1.6</target>
@@ -104,7 +104,7 @@
       <plugin>
         <groupId>com.samskivert</groupId>
         <artifactId>depot-maven-plugin</artifactId>
-        <version>1.0.2</version>
+        <version>1.0.4</version>
         <executions>
           <execution>
             <id>genrecord</id>
@@ -126,7 +126,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-resources-plugin</artifactId>
-        <version>2.7</version>
+        <version>3.0.2</version>
         <configuration>
           <encoding>UTF-8</encoding>
         </configuration>
@@ -135,7 +135,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
-        <version>2.18.1</version>
+        <version>2.20</version>
         <configuration>
           <excludes>
             <exclude>com/samskivert/depot/TestCacheAdapter*.java</exclude>
@@ -148,7 +148,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-javadoc-plugin</artifactId>
-        <version>2.10.3</version>
+        <version>2.10.4</version>
         <configuration>
           <quiet>true</quiet>
           <show>public</show>
@@ -164,7 +164,7 @@
       <plugin>
         <groupId>org.sonatype.plugins</groupId>
         <artifactId>nexus-staging-maven-plugin</artifactId>
-        <version>1.6.6</version>
+        <version>1.6.8</version>
         <extensions>true</extensions>
         <inherited>false</inherited>
         <configuration>