make dependency on commons-io explicit (#15)

* make dependency on commons-io explicit

Author: elharo

pom.xml

@@ -105,7 +105,13 @@
  <artifactId>sisu-inject-plexus</artifactId>
  <version>1.4.2</version>
  </dependency>
-
+ 
+ <dependency>
+ <groupId>commons-io</groupId>
+ <artifactId>commons-io</artifactId>
+ <version>2.6</version>
+ <scope>test</scope>
+ </dependency>
  <dependency>
  <groupId>org.easymock</groupId>
  <artifactId>easymock</artifactId>