Fix toast timeout bug

[alexrussell]

Save the timeout ID when a toast is shown so that we can clear any existing timeout when a new toast is shown so that an old timeout doesn't close a new toast prematurely.

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Replaces #1324 as I accidentally deleted my branch when trying to tidy up. Also I have redone the work on top of the latest master.

@jswxwxf you should now follow this issue.

[SupriyaKalghatgi]

@alexrussell Thank you for the update!

[eassymo]

Another Toast timeout bug is when duration is not defined or is zero (0), Toast should be sticky or permanent but Toast auto-close after shown, otherwise add a property called "sticky" or "closeByButton", anything, but we could not have a sticky toast.

Out of "timeout" toping, Toast should be "swipeable" and call "onClose" event when timeout or swiped, and buttonText should have another action like "onPress" not call onClose.

[SupriyaKalghatgi]

@eassymo Toast takes default value of 1500 for duration

[alexrussell]

@eassymo You should open up some issues from what you said here as some make sense to me. I think I can see at least three separate issues you can open here:

1. There should be some way to make a permanent (i.e. must be dismissed) toast. Either setting timeout to a special value (0, -1) or using a specific config of permanent: true or autohide: false, etc.
2. Toasts to be swipeable to dismiss
3. Separate callbacks for the way that a toast was closed. In order to conserve BC I imagine we need to leave the current onClose as happening when the toast closes through click or timeout, but introduce two more: onDismiss that only gets called if the toast was user-dismissed and onAutoClose that only gets called if the toast closed due to the timeout expiring.

[ahartzog]

Created a PR for onDismiss --> https://github.com/GeekyAnts/NativeBase/pull/2678/files