feat(): assume NodeList

fromEvent() now assumes it is passed a NodeList and creates
a single stream from all of the elements of a NodeList.

Closes #17

src/fromEvent.js

@@ -1,5 +1,6 @@
 import Stream from 'most/lib/Stream'
 import MulticastSource from 'most/lib/source/MulticastSource'
+import forEach from 'fast.js/array/forEach'
 
 const tryEvent =
   (t, x, sink) => {
@@ -40,12 +41,17 @@ EventAdapter.prototype.dispose = function dispose() {
 
 const initEventTarget =
   (source, event, addEvent, useCapture) => { // eslint-disable-line
-    source.addEventListener(event, addEvent, useCapture)
+    forEach(
+      source,
+      s => s.addEventListener(event, addEvent, useCapture)
+    )
 
-    const dispose =
-      (_event, target) => {
-        target.removeEventListener(_event, addEvent, useCapture)
-      }
+    const dispose = (_event, target) => {
+      forEach(
+        target,
+        t => t.removeEventListener(_event, addEvent, useCapture)
+      )
+    }
 
     return dispose
   }
@@ -70,7 +76,7 @@ EventTargetSource.prototype.run = function run(sink, scheduler) {
 const fromEvent =
   (event, source, useCapture = false) => {
     let s
-    if (source.addEventListener && source.removeEventListener) {
+    if (source[0].addEventListener && source[0].removeEventListener) {
       s = new MulticastSource(
         new EventTargetSource(event, source, useCapture)
      )