[Android] Backport Python 3 make_apk fixes for crosswalk-8.

This pull request backports #2303 to the crosswalk-8 branch. Original pull request message:

> [Android][REG] Packaging tool does not work with python 3.0+
>
> 1. command output is a bytes-like object in python3.0+,
> re.findall can't use a string pattern on a bytes-like object,
> encode the bytes-like object to str to fix that.
> 2. map function will return a map object in python3.0+,
> 'map' object has no attribute 'extend',
> not use map function to fix that.
>
> BUG=https://crosswalk-project.org/jira/browse/XWALK-2303

BUG=XWALK-2474