Update docs/api-guide/authentication.md

Added mod_wsgi specific instructions
Update docs/api-guide/authentication.md

refined mod_wsgi
Add nested create for 1to1 reverse relationships
Remove commented out debug code
Update one-to-one test names
Update errant test comment
Add one-to-one nested update and delete functionality
Move nested serializer logic into .field_from_native()
Use None to delete nested object as opposed to _delete flag
Merge pull request #556 from maspwr/one-to-one-nested

One-to-one writable, nested serializer support
Revert accidental merge.
Raise Validation Errors when relationships receive incorrect types. Fixes #590.
Update release notes.
Note on setting ContentType. Fixes #589. Refs #586.
Drop the curl notes.  Unnecessary.
Merge pull request #588 from nemesisdesign/patch-1

mod_wsgi specific documentation for WSGIPassAuthorization
Rephrasing.
Added @nemesisdesign, for documentation on Apache mod_wsgi setup. Thanks!

Refs #588.
Drop unneeded test