build problems with the saveVersion.py script

Currently the saveVersion.py has the following problems:

• it doesn't work with python3 due to 'inconsistent whitespace usage' and because in python3 the byte array is different from a string
• The checksum is generated from all the java source files from ranger-util/target, which contains at most one java file - a previously generated ranger-util/target/gen/org/apache/ranger/common/package-info.java