Add commons codec depdency to pom

Tried building against alpha-2 release and it failed to find commons
codec.  Maybe it used to get it transitively from Accumulo.
diff --git a/pom.xml b/pom.xml
index b03c116..deb0ed2 100644
--- a/pom.xml
+++ b/pom.xml
@@ -143,6 +143,11 @@
       <version>1.10</version>
     </dependency>
     <dependency>
+      <groupId>commons-codec</groupId>
+      <artifactId>commons-codec</artifactId>
+      <version>1.11</version>
+    </dependency>
+    <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-math3</artifactId>
       <version>3.6.1</version>