getAsString in Definitions namespace

[arykov]

If wsdl is loaded from a file, modified and then exported using getAsString() it gets generated in default namespace. If the original wsdl was defined with a namespace prefix and default namespace was not defined or was defined as something other than http://schemas.xmlsoap.org/wsdl/, wsdl produced using getAsString will be invalid due to incorrect namespace.

See attached test case
NamespaceTest.txt