Annotation Tools: Adding Loading Bar to Annotations Table

**Background:** Quick and easy fix to slow loading of annotations: To make it easier for people with slower connections and people dealing with our annotations backend, we've added a loading bar below the grid during loading of the annotations.

**Studio Updates:** None.

**LMS Updates:** If our backend is being slow or non-responsive, a loading bar should appear when switching between "MyNotes" and "Public" tabs. In theory most people should not see it (or should only be able to glance at it). A good way to test is to not put down a backend. It should just show a loading gif and a message telling people to please wait.

**Test:** Set up text annotation via advanced_modules in "Advanced Settings". Load the component in a module and head over to the LMS. Once there switch between the Public and MyNotes tabs to see the message appear. If connected to a server it should disappear within milliseconds in an average connection. A slow connection might have it up for longer. If there are issues with the backend, it should just stick around and not disappear (a message should pop up on the top of the screen once the call times out saying they can't connect to the backend). 
spacing before and after `//`

Also I'm going to quit commenting about usages of `!=` and `==` - there are quite a few in this diff and like I said before my JS-foo isn't super strong to know when one use is appropriate over another.