add jruby-head back in as allowed failure
add jruby-head back in as allowed failure

kou/ffi-yajl,kou/ffi-yajl,kou/ffi-yajl,chef/ffi-yajl,chef/ffi-yajl,h4ck3rm1k3/ffi-yajl,chef/ffi-yajl,h4ck3rm1k3/ffi-yajl,h4ck3rm1k3/ffi-yajl