ported earlier work on namespaces, moved out simple.prop property

lib/dom/document.js
+ implemented createElementNS

lib/dom/element.js
+ implemented getAttributeNS, setAttributeNS methods

lib/dom/node.js
+ implemented prefix and localName properties (getters)
+ implemented lookupPrefix and isDefaultNamespace methods
* factored out simple.prop for baseURI property (getter)

lib/simple/factory.js,
lib/simple/serializer.js
lib/simple/simple.js
+ added support for namespaces

lib/processor/handler.js
* changed validTagnames expression to allow for ':', '_', '-' in tags

lib/dom/namednodemap.js
* now sports a proper init function

lib/dom/documenttype.js
- factored out this.prop

test/namespace.js
+ added tests for namespaces
marked several namespace related methods as 'done' in the readme