rewrite in python

[anantshri]

just a warning issue.
in case this shell script goes out of hand with complexity it might make sense to port this over to python for better managability.

[c0dist]

Just a note to anyone picking: We need to make sure that the syntax to use apk2java remains the same, in case someone has already wrote something that calls this. The general syntax to use right now is,

apk2java <APK_PATH> <OPTIONAL_DESTINATION>