revert fix SPARK-1629: Spark Core missing commons-lang dependence

Author: witgo

core/pom.xml

@@ -113,10 +113,6 @@
       <groupId>commons-net</groupId>
       <artifactId>commons-net</artifactId>
     </dependency>
-    <dependency>
-      <groupId>commons-lang</groupId>
-      <artifactId>commons-lang</artifactId>
-    </dependency>
     <dependency>
       <groupId>${akka.group}</groupId>
       <artifactId>akka-remote_${scala.binary.version}</artifactId>

pom.xml

@@ -371,11 +371,6 @@
         <artifactId>commons-net</artifactId>
         <version>2.2</version>
       </dependency>
-      <dependency>
-        <groupId>commons-lang</groupId>
-        <artifactId>commons-lang</artifactId>
-        <version>2.6</version>
-      </dependency>
       <dependency>
         <groupId>io.netty</groupId>
         <artifactId>netty-all</artifactId>