Annotation Tool: Fixed Flagging for Instructor flag removal

**Goal:** Instructors should be able to a) view how many times an annotation has been flagged and b) remove all flags from their own annotations.

**Studio Updates:** None.

**LMS Updates:** If you are marked as instructor (instructor email in the settings for the component), you should be able to see how many people have flagged your annotation and if you can edit the annotation you should be able to remove all flags associated with that annotation (note: not individual flags, all of them). If you are not an instructor, then nothing will have changed for you.

**Testing:**  Initiate the annotation components using Advanced Settings to add advanced modules, annotation storage url, and secret token. Create a new unit and add a text annotation component. Set yourself as instructor. In the LMS create an annotation. Hover (you should see nothing new) and hit edit (you should see nothing new). Now hover again and hit the flag in the top right corner. The flag should now be black. If you move out and hover again it should now tell you that the annotation has been flagged once. Now if you hit edit, you will see the option to check a box if you would like to remove the flagged annotations. Otherwise leave it unchecked and save or hit cancel. 
Additionally for a string like this one, you'll want to use `ngettext` like so: https://github.com/edx/edx-platform/blob/master/cms/static/js/views/group_configuration_details.js#L59