Appdaemon: Use newest python version when installing.

[ludeeus]

Description:

This will use the newest version of python installed on the unit when creating venv.

Related issue (if applicable): Fixes #154

Checklist (Required):

• The code change is tested and works locally.
• The code is compliant with Contributing guidelines

If pertinent:

• Script has validation check of the job.
• Created/Updated documentation at /docs

[Landrash]

I believe your overcomplicating this one. python3 will symlink to whatever version is installed ;)

pi@hassbian:~ $ ls -la /usr/bin/python3
lrwxrwxrwx 1 root root 9 Jan 20  2017 /usr/bin/python3 -> python3.5

[ludeeus]

That depends on how (if) you upgraded python.
I have 3.6 installed, and it still points to 3.5

pi@hassbian:~$ which python3.6
/usr/local/bin/python3.6
pi@hassbian:~$ ls -la /usr/bin/python3
lrwxrwxrwx 1 root root 9 Jan 20  2017 /usr/bin/python3 -> python3.5

[Landrash]

Seems like a odd workaround but well include it since for some reason building newer python versions are not updating symlinks properly.