Feature/predefined normalization

fix #67 and [jubatus#255](https://github.com/jubatus/jubatus/issues/255)

I implemented 3 normalization `num_filter`
- linear scale normalization(o to 1 with/without truncate)
- gaussian normalization(-1 to 1 normalization)
- sigmoid normalization(0 to 1)

get_with_default does not return a reference. https://github.com/jubatus/jubatus_core/blob/master/jubatus/core/fv_converter/util.hpp#L31