set cache dir depth at construct time. fix #5

commit 539e18b0c4336dea378901092d0a06e6f1109749
Author: SebSept
Date:   Wed Jan 15 22:32:18 2014 +0100

    set pathDepth at construction : implementation. Fix #5

commit 6c84582566faced19b2876d28155b6989a1f715e
Author: SebSept
Date:   Wed Jan 15 22:30:05 2014 +0100

    fix $delay initial value and doc

commit 0f1ebe32d8a3ef33e93e8df9209f2e5b78a75a5e
Author: SebSept
Date:   Wed Jan 15 22:23:04 2014 +0100

    set pathDepth at construction : test