Prepare porting pficommon for Jubatus

Create jubatus/util directory and ported pfi/pficommon module for Jubatus. We decided to port pficomon for Jubatus at the regular meeting.
This PR contains below instruction 1 to 3, and wscript modified for installing jubatus_util shared object and headers.
https://gist.github.com/suma/589470bcf50c5605960e (written in Japanese)

We need to remove pficommon dependency and to use ported jubatus_util when this PR merged.