When building an app via python-for-android (without using buildozer on top of it), the app may fail to build.

python-for-android refuses to build due to a python file that is located in a blacklisted folder (via blacklist.txt) as that file is failing the byte-compile step.

That should not happen, as a blacklisted folder (E.g. venv or .git) may contain a python file that can't be byte-compiled.
Also, byte-compiling a blacklisted folder may lead to an increase of the build time.

This PR targets the above-mentioned issue, and the following minor ones:

• As of Python 3.5, the .pyo filename extension is no longer used and has been removed in favour of extension .pyc
  All the references to pyo has been removed. --no-compile-pyo build option has been removed in favor of --no-byte-compile-python, which doesn't refer to a specific filename extension.
• .apk and .aab are not blacklisted by default. The first ever build will work, but the subsequent one will try to also include the .apk or .aab into the artifact. That will lead to an increase in size and a potential failure during the final gradle step.