In LMS, load OVA JS only in four OVA templates with requireJS. [TNL-693]

To avoid having OVA JS files loaded in every page of the LMS and therefore clash with edXNotes, remove their entries from ```PIPELINE_JS``` in ```common.py``` and load them instead, via requireJS, in the 4 OVA templates: ```imageannotation.html```, ```notes.html```, ```text annotation.html```, and ```videoannotation.html```.

@jimabramson, @explorerleslie Please review.

Alternatively, we can also load the OVA JS in the 4 templates by using ```PIPELINE_JS``` and defining a new group called ```ova_js```:
https://github.com/edx/edx-platform/compare/jmclaus/load_ova_js_from_templates

This runs into a problem though. The following line for example will always be executed:
https://github.com/edx/edx-platform/blob/5cc0e023103475850c6ad1d77fa0a31605f69bb9/lms/templates/videoannotation.html#L203
But in Studio, we'd like to use requireJS:
https://github.com/edx/edx-platform/blob/5cc0e023103475850c6ad1d77fa0a31605f69bb9/lms/templates/videoannotation.html#L206
> So if I understand correctly, under the present setup, performance/behavior improves a little for most pages since ova is not loaded all the time anymore, otherwise it's unchanged.

> On the few pages using ova:
a) first load performance will degrade somewhat due to adding a number of new individual files to download
b) a user behind a proxy that refuses to cache urls with query strings will be downloading all these files on all loads, not just the first.

@jimabramson 

a. Correct, we are stripping 18 JS OVA files from from LMS main vendor. That should improve loading time a little for most pages. And yes, for the few pages using OVA, it will degrade things as the files will be loaded there by requireJS as 18 separate entities. But they will not block page rendering.

b. Indeed, some proxy servers may not cache these JavaScript files but we still have client-side caching by browser after first load.