CORD-742 Add xpath

Change-Id: Icdca309e50680d9f552f03af50ca7d210f83fe92
diff --git a/ansible/roles/buildtools/defaults/main.yml b/ansible/roles/buildtools/defaults/main.yml
index b4776bb..9cca96e 100644
--- a/ansible/roles/buildtools/defaults/main.yml
+++ b/ansible/roles/buildtools/defaults/main.yml
@@ -1,3 +1,4 @@
 apt_packages:
   - maven
   - git=1:2.11*
+  - libxml-xpath-perl