added creation of dirs, the concrete scenario is that I want to create a visualee folder under the target/site folder in a maven based project - and I do not want to couple the "build" and the "site" lifecycle. Thus I need to be able to create a complete path.
added tests for the dir creation
Merge pull request #1 from AllanHoejgaardJensen/master

Added the ability to create directory structures for the output directory