Array traversing for children opts - closes #1070

This should allow two additional ways to specify children for turning on specific components and ordering them:

````
children: [
  'comp1',
  'comp2',
  'comp3'
]
````
````
children: [
  { comp1: {} },
  { comp2: {} },
  { comp3: {} }
]
````

There is no an additional `vjs.each`, which can handle either objects or arrays