Annotation Tools: Added Grouping Plug-In

**Background: ** During our last course launch we noticed that if hundreds of people are annotating a text, it all very quickly overlaps and the text becomes chaotic and unreadable. This update adds a "Grouping" button that can be toggled on or off that would group annotations based on line position.

**Studio Updates: ** None.

**LMS Updates: ** Only in text annotations you should see a new button pop up that shows whether grouping is turned on or off. Add any number of annotations and those that **begin** on the same line will get added to the group. Clicking on that group will show only the annotations that are contained with in that group. 

**Testing:** Add the text annotation tool via "advanced modules" in Advanced Settings for the course. Then make sure annotation_storage_url and annotation_secret_token are set. Head over to a unit and add the component. whenever you add annotations, if the button says that the grouping is on then the highlighting will not show up, but rather a sidebutton with the number "1" or whatever number of annotations you've added. Default for Public is grouping turned on and default for everything else is grouping turned off. 
Just curious - is there a better message you could provide here (perhaps what the problem might be / why it's not supported)?