Update commons-parent 50 to 51

Remove pre-jdk8 profile version control for plugins that are now
controlled by the parent.
diff --git a/pom.xml b/pom.xml
index fc03467..0c6d295 100644
--- a/pom.xml
+++ b/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>org.apache.commons</groupId>
     <artifactId>commons-parent</artifactId>
-    <version>50</version>
+    <version>51</version>
   </parent>
 
   <artifactId>commons-rng-parent</artifactId>
@@ -562,12 +562,6 @@
       <activation>
         <jdk>[1.6,1.8)</jdk>
       </activation>
-      <properties>
-        <!-- Override parent version 4.x which requires Java 8. -->
-        <commons.felix.version>3.5.1</commons.felix.version>
-        <!-- Override parent version 1.18 which requires Java 8. -->
-        <commons.animal-sniffer.version>1.17</commons.animal-sniffer.version>
-      </properties>
       <build>
         <!-- Alter default goal as it uses checks from Java 8 plugins. -->
         <defaultGoal>clean verify</defaultGoal>