EnableNetwork ignores wait if already enabled

[karalabe]

If the node already has networking enabled - but has not yet finished building its circuits - EnableNetwork will abort at https://github.com/cretz/bine/blob/master/tor/tor.go#L370 even if wait set set to true. This might have unintended side effects for code that expects the circuits to be done, e.g. https://github.com/cretz/bine/blob/master/tor/listen.go#L259

[cretz]

Hrmm, I suppose the fix here is to have enable network check bootstrapped even when already enabled. May still have event part ahead of time set per #40. Will investigate.