0.4.0 release has missing pom from maven central

[gaborgsomogyi]

I've just analyzed through why pemja 0.4.0 is not found and the reason is that:

• 0.3.0 has pom inside: https://repo.maven.apache.org/maven2/com/alibaba/pemja/0.3.0/

  

• 0.4.0 has no pom inside: https://repo.maven.apache.org/maven2/com/alibaba/pemja/0.4.0/

  

[HuangXingBo]

I will release 0.4.1 asap.