This change causes site_config_dir function to return
/etc/cheat on linux systems. This is right because most
linux distributions follow FHS where /etc is a directory
which contains system-wide configuration files.
The prior attempt to resolve#420 and #431 relied on `appdirs` to
determine the appropriate directories into which to install files.
Previously, `setup.py` dynamically attempted to install `appdirs` via
`pip` during installation if necessary.
This attempt to failed on multiple platforms, however, due to
backwards-incompatible `pip` interfaces.
As a workaround, I have now directly included `appdirs` (a small module)
within `cheat` itself. This approach is explicitly supported per the
`appdirs` documentation:
https://pypi.org/project/appdirs/
Tomas Korbar
Chris Lane