Flowerhack/feature/bulkemailnewdash

Bulk email added to new dashboard

@sarina @adampalay 

One question I had: I looked into this and, on my local machine, it seemed like I needed to set ENABLE_INSTRUCTOR_EMAIL to True in lms/envs/common.py to make bulk emailing work.  Does anyone have any confirmation or insight on this?  I'm a little nervous changing a massive settings file for fear of blowing something else up