Setuptools for Python3 (Crystax)

[AndreMiras]

Adds python3crystax support to setuptools recipe.
Also removed unused imports.

Before the fix, running buildozer android debug was resulting the following:

[INFO]:    No existing dists meet the given requirements!
[INFO]:    No dist exists that meets your requirements, so one will be built.
[ERROR]:   Didn't find any valid dependency graphs.
[ERROR]:   This means that some of your requirements pull in conflicting dependencies.
[ERROR]:   Exiting.
# Command failed: /usr/bin/python -m pythonforandroid.toolchain create --dist_name=myapp --bootstrap=sdl2 --requirements=python3crystax,kivy,setuptools --arch armeabi-v7a --copy-libs --color=always --storage-dir=/home/ubuntu/demo/.buildozer/android/platform/build
# 
# Buildozer failed to execute the last command
# The error might be hidden in the log above this error
# Please read the full log, and search for it before
# raising an issue with buildozer itself.
# In case of a bug report, please add a full log with log_level = 2

Test program:

from kivy.app import App
from kivy.uix.label import Label
import pkg_resources


class MyApp(App):

    def build(self):
        version = pkg_resources.get_distribution("setuptools").version
        return Label(text="version: " + version)


if __name__ == '__main__':
    MyApp().run()

Side note, this is a simple fix to merge, but it actually requires few more changes to pythonforandroid/recipe.py and pythonforandroid/recipes/hostpython3crystax/__init__.py that are soon to come.

[inclement]

Thanks!

[AndreMiras]

Super fast, thanks!