Unpipe EventHandlers from faPipeTo and faPipeFrom when their scopes are destroyed

I made a little service/helper called $famousPipe because the node/array-of-nodes listener setup was pretty similar between faPipeTo and faPipeFrom, and figured we might as well also support arrays for both. (I can imagine actually wanting this later as the directives library becomes more mature....)

Anyway, in case you don't like this approach, the main bug I was trying to fix is "event handlers aren't unpiped when scopes of faPipeTo/faPipeFrom directives are destroyed"...so that's the only part that is an actual bugfix.