Error when path does not exist

When you provide a non-existent entry to findit, an error occurs. You can reproduce it with:

    findit.find('/path/to/anything')

This pull request fixes it.

The only thing that questions me is about the 'end' event. I have it triggered in the PR, but I'm not sure whether it is a good thing. I'm relying on you on this one ;)

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Fixes #17 and #15