some more fixes for the nillable quirk.
minor
make customized types inside 'XmlModifier's work. #293
fix typo in TwistedWebResource that makes wsdl requests work again. #294
Merge branch 'master' of github.com:arskom/spyne
Added CONTRIBUTING.rst file.
Merge pull request #298 from warvariuc/contributing-policy

Added CONTRIBUTING.rst file.
Move all contribution info to readme. #298
add unit test guideline
Merge pull request #299 from plq/master

Document Updates. Contuniation of #298