fix #565: setup data after config loaded

[akyrey]

@rusnasonov thank you for the PR.

What about leaving the data initialization and sync_on_change function also inside Harpoon::new() and edit Harpoon::setup() like you did but with sync_on_change(self) moved right before the final return?

[rndev-io]

What about leaving the data initialization and sync_on_change function also inside Harpoon::new()

It's creates additional empty data file with default key, which will never be used. If it's ok - why not.

but with sync_on_change(self) moved right before the final return?

Ok

[maxrzaw]

This also fixes #577