Docstring update (#58)

* migrate docstrings from reST to google format

* add raises note

Also change behaviour of the `from_option` method to fallback to
disabled instead of raising exception on unknown option

* fix part of warnings for sphinx

* make identation a bit more readable

* review fixes

* add verbose description for properties to make them parsed by sphinx extenstion

* add demo sphinx generator

docs/source/ahriman.core.auth.rst

@@ -0,0 +1,50 @@
+ahriman.core.auth package
+=========================
+
+Submodules
+----------
+
+ahriman.core.auth.auth module
+-----------------------------
+
+.. automodule:: ahriman.core.auth.auth
+   :members:
+   :no-undoc-members:
+   :show-inheritance:
+   :private-members:
+
+ahriman.core.auth.helpers module
+--------------------------------
+
+.. automodule:: ahriman.core.auth.helpers
+   :members:
+   :no-undoc-members:
+   :show-inheritance:
+   :private-members:
+
+ahriman.core.auth.mapping module
+--------------------------------
+
+.. automodule:: ahriman.core.auth.mapping
+   :members:
+   :no-undoc-members:
+   :show-inheritance:
+   :private-members:
+
+ahriman.core.auth.oauth module
+------------------------------
+
+.. automodule:: ahriman.core.auth.oauth
+   :members:
+   :no-undoc-members:
+   :show-inheritance:
+   :private-members:
+
+Module contents
+---------------
+
+.. automodule:: ahriman.core.auth
+   :members:
+   :no-undoc-members:
+   :show-inheritance:
+   :private-members: