http: fix plain Maven build
diff --git a/core/plugins/org.eclipse.hawk.http/pom-plain.xml b/core/plugins/org.eclipse.hawk.http/pom-plain.xml
index 8ad3aa5..061604f 100644
--- a/core/plugins/org.eclipse.hawk.http/pom-plain.xml
+++ b/core/plugins/org.eclipse.hawk.http/pom-plain.xml
@@ -23,5 +23,10 @@
 	    <groupId>org.apache.httpcomponents</groupId>
 	    <artifactId>httpclient</artifactId>
     </dependency>
+    <dependency>
+      <groupId>commons-io</groupId>
+      <artifactId>commons-io</artifactId>
+      <version>2.2</version>
+    </dependency>
   </dependencies>
 </project>