minor change to ssh pub key env variable

Author: doublerr

kitchen.jenkins

@@ -5,7 +5,7 @@ driver:
   rackspace_username: <%= ENV['rackspace_username'] %>
   rackspace_api_key:  <%= ENV['rackspace_api_key'] %>
   rackspace_region: 'DFW'
-  public_key_path: <%= ENV['SSH_KEY_FILE'] %>
+  public_key_path: <%= ENV['SSH_PUB_KEY_FILE'] %>
 
 platforms:
 - name: centos-6.4