Integrate ClassyShark with Proguard mappings.txt file

[borisf]

Thanks https://github.com/Dorvaryn

Steps:

1. Read the mappings file
2. Add callback here https://github.com/google/android-classyshark/blob/master/ClassySharkWS/src/com/google/classyshark/silverghost/translator/java/JavaTranslator.java

[borisf]

thanks @Dorvaryn

[borisf]

thanks @dextorer for tech insights & tradeoffs

[borisf]

added class names mapping. Looking forward from community to see what is missing, and open new bugs for missing features