Spcify pficommon's license on README.
Merge pull request #897 from gwtnb/pficommon-license

Spcify pficommon's license on README.
detect logger configuration failures (fix #895)
fix to use exit(1) instead of abort
Merge pull request #902 from jubatus/fix-895

detect logger configuration failures (fix #895)
bump version 0.6.5 -> 0.6.6