add proguard support
https://github.com/wvengen/proguard-maven-plugin/blob/master/pom.xml
<groupId>net.sf.proguard</groupId>
<artifactId>proguard-base</artifactId>
# mvn dependency:get -Dartifact=net.sf.proguard:proguard-base:6.0.3
Edited by axet