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
test mandatory elements
test mandatory subelements
test mandatory element attributes
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
Refactored classes to use ``super`` where applicable.
automatically set use="required" for mandatory elements inside XmlAttributes #297
deprecate spyne.model.primitive.Mandatory
minor
update contributing.rst
Merge branch 'master' of github.com:arskom/spyne
use mandatory wrapper from `spyne.model.complex`