Fix: Update the 'conf.py' File for Sphinx

Trying to make things nice for readthedocs.org.
Fixed: Cleanup as Recommended by Sphinx
Fixed: Removed Unused 'sphinx_rtd_theme' from optional_requirements.txt
Fixed: Improve API (Installation and Known Issues)

This has been a for-a-while-standing problem.

Closes #286
New: Release 1.2.3 (to Prompt readthedocs.org to Build)