0.5.0

• Make tests pass on NetBSD, #37
• Don't close file descriptors since dup2 will close it atomically before dup, #41
• Replace dependency tempdir with tempfile, #42
• Replace try! with ?
• Don't leak pid file into children, #39
• Remove boxfnonce dependency
• Hide error kinds
• Hide Group implementations
• Hide User implementations
• Add Mask type
• Add an option to keep parent process alive after daemonize
• Wait for the first child to fork
• Ensure pid file ends with line separator