0.3.9

Bug fix

• No output file while using [chunkhash] in filename #101 @CJY0208

Internal

• Remove mkdirp. #96 @wtgtybhertgeghgtwtg
• Replace merge utility with spread syntax. #97 @wtgtybhertgeghgtwtg
• Replace concat utility with spread syntax. #98 @wtgtybhertgeghgtwtg
• Replace keys utility and lodash/keys with Object.keys. #100 @wtgtybhertgeghgtwtg