Bok-Choy CMS Video Tests

Bok-Choy tests for [video.feature](https://github.com/edx/edx-platform/blob/master/cms/djangoapps/contentstore/features/video.feature)

@auraz @polesye @jzoldak 
me too :)

Actually the selector is directly selecting the newly created video component and then ensure that it is indeed a video component.

Your selector will get all the xblock components and then ```any``` will return ```True``` if any of the component is of type video whether the newly created component is of type video or not.

we can use your suggestion with a change in last line below
```python
if xblock_components_after == 2 and 'video' == xblock_component_types[1]:
```
this will ensure that the second(newly created) component is indeed video.