Merge branch 'release/0.4.5' into develop
Add Oniguruma.

Jubatus 0.5.0 replace re2 with oniguruma.
This commit follows it.
Add -r option to switch regexp library
Merge pull request #20 from jubatus/add-switch-regex-lib-option

Add -r option to switch regexp library
Remove pficommon
Merge pull request #22 from jubatus/remove-pficommon

Remove pficommon
bump version
Merge branch 'release/0.5.0'