deal with upcoming java reflection security

[alee]

Will need to do something about xstream serialization, either disable it or figure out how to permit "illegal" access.

     [java] WARNING: An illegal reflective access operation has occurred
     [java] WARNING: Illegal reflective access by com.thoughtworks.xstream.core.util.Fields (file:/home/alllee/workspace/foraging/lib/xstream-1.4.10.jar) to field java.util.TreeMap.comparator
     [java] WARNING: Please consider reporting this to the maintainers of com.thoughtworks.xstream.core.util.Fields
     [java] WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
     [java] WARNING: All illegal access operations will be denied in a future release

x-stream/xstream#101