Merge pull request #26 from kevinsawicki/whitespace

Remove trailing whitespace
Merge pull request #27 from kevinsawicki/duplicate-dev-dependencies

Remove duplicate devDependencies key
Require xmlbuilder if it is undefined

Previously this would only be required if window was undefined
but checking instead for xmlbuilder being undefined allows this
to be used in contexts that have a window but do not provide
xmlbuilder.