Add pficommon for porting
Fix wscript for jubatus/util
Change pfi:: namespace to jubatus::util
Change jubatus/util include guard for avoiding confclit

This commit changed ported pficommon headers.
Add README to jubatus/util
Rename pfi-config.h util-config.h
Merge pull request #467 from jubatus/feature/pficommon-port

Prepare porting pficommon for Jubatus