#17 Completion info doesn't update until document is reparsed

[Ian Lewis]

If you add an element with namespace info, i.e. an
xmlns attribute to the the completion info for that
node is not added to the node. Not until XMLDocument
parses the document again does the completion info get
added.

Unit Test:

1.) In the tree view, add an 'html' element to a newly
created file.
2.) Add an
xmlns="http://www.w3.org/TR/xhtml1/transitional"
attribute to the html element.
3.) Right clicking on the node and going to Add->Add
Element-> shows no completion info (bug).
4.) Go to the source view and add a space somewhere to
the document.
5.) Remove the space and go back to the tree view.
3.) Right clicking on the html node and going to
Add->Add Element-> shows the correct completion info.