Added sync argument to Project constructor/runCopy

OSX has a max limit on open file descriptors. This can sometimes get in the way of copying. Adding sync method for synchronous copying of files is a nice band-aid for OSX users looking to copy many files within the same process. Now we can do this:

`var project = Guilder(srcFolder, destFolder, /darwin/.test(process.platform));`
Merge pull request #2 from shennan/patch-1

Added sync argument to Project constructor/runCopy