General Code Clean

- Made normal Python files PEP8-compliant
- Made Cython files roughly PEP8-compliant
- Added space between docstring end and code begin
- Made single-line docstrings actually single line
- Add line to tox.ini to run PEP8 on Cython files
- Deleted old, unused files
- Added ordering to imports: alphabetical, first system, then space
  the cimports then space, then Python imports
Added not about why GSS_C_EMPTY_BUFFER is not used
Use GSS_C_INDEFINITE for TTLs

Previously, we would use 0 to mean indefinite.  While this works,
it's not in compliance with the spec, which says to use
GSS_C_INDEFINITE.  Now, when "None" is passed to a ttl, it becomes
GSS_C_INDEFINITE, and vice-versa.
Add in support for GSS_C_NO_NAME

GSS_C_NO_NAME is returned by some methods, and used as input
by others.  This adds support for converting None to GSS_C_NO_NAME
in the appropriate places, and vice-versa.