Python Scripts Reorganized - UG1602

The Python scripts are reorganized:

• A new sfptpd-python3 RPM package contains all the Python code.
• The base sfptpd package does not depend on Python.
• The chrony control script has been moved to /usr/libexec.
• Chrony clock control can now be enabled with clock_control on instead of specifying a path to the helper script.
  Note: Configurations using the old example chronyd script location have the new location substituted for compatibility, but you are advised to replace this with a simple clock_control on configuration unless this script has been customized for your system.