#3 pep8 changes prior to adding new tests

includes a bug fix in HTTP: credential removal wasn’t working.  Also
includes a bug fix in OData core regression tests as Many2Many
recursive one-way navigation tests were being skipped
#5 doc changes, less aggressive test
#3 refactor for pep8
#5 media stream support changes

Includes changes for auto-generation of entity keys (Int32, Int64 and
String) and a chunked encoding reader for dealing with WSGI
implementations that fail to remove it.
#7 new odata cmd line tools

Adds odatadiff.py for comparing old and new versions of the same OData
service (useful during development) and odatadoc.py which generates an
xhtml documentation file from an OData metadata document.