[Android] Fix packaging tool can't work on python3.0+.

1. Change print to print function.
2. Change "except" expression for try..catch
3. Add decode("utf-8") for output of subprocess
4. Change "filter" and "file" uncompatible usage.
5. Move ant.py and md5_check.py into xwalk, which request modification.

BUG=https://crosswalk-project.org/jira/browse/XWALK-766