add an example config for v0.12's filter

to be the basis for the upcoming documentation
add tests for path with time_slice_format
Merge pull request #488 from fluent/enhance_test_out_file

add tests for path with time_slice_format (out_file)
Merge pull request #482 from kiyoto/master

add an example config for v0.12's filter
add new csv formatter
fix tests to use data-driven approach