Added decorator to optionally call the Content-Type processors

The custom Content-Type processors did not respect CherryPy's flag to
optionally not process the request body.
Do not process the request body if Content-Length is empty or missing
Added decorator to optionally call the Content-Type processors

The custom Content-Type processors did not respect CherryPy's flag to
optionally not process the request body.
Replace the current session after expiring it
Content-Length value is a string
Moved loading the auth module from the method to the class __init__

Refs #61
Added salt import; removed unused salt.output import
Use yaml.safe_dump instead of yaml.dump to coerce Python objects

This was outputting unicode strings as Python objects.
Fixed docstring for consistency with the actual file name
Bumped version number to 0.8.0
Added release notes for 0.8.0
Added requirements.txt to MANIFEST.in
Add default if ``debug`` is not set in config
Fix logout URL in release notes.
Merge pull request #68 from holmboe/docfix-logout-url

Fix logout URL in release notes.
Added installation instructions for packages

Fixes #47
Updated link on docs home to describe installation not development
Fixed links to rest_cherrypy
Added openSUSE package instructions
require cherrypy and saltmaster