Caijim/emaillist

Backend+Frontend code for Email List tool on instructor dashboard page (under membership tab)

A few things:
1) Javascript is not clean. Any pointers would be greatly and graciously appreciated
2) In the urls file, I had to double up on some urls like the following just so I could call reverse(..) on them (see instructor_dashboard.py) so I could use the parameterized version in js. If I don't add the non-param'd version the page doesn't load. What is the way around this?

url(r'^get_single_query/(?P<inclusion>\S{2,3})/(?P<queryType>(Section|Problem))/(?P<stateType>\S+)/(?P<stateId>\S+)$', 'instructor.views.api.get_single_query', name="get_single_query"),
(r'^get_single_query',
  'instructor.views.api.get_single_query', name="get_single_query")


Thanks, and sorry for the huge changelist

tagging @jbau @stvstnfrd @kluo  for reviewing

Since we need to wrap this line anyway, we should do so at ~80
characters:
```html
<label for="beginning_specific">
    Select criteria on which to generate a list of student emails.
    Please clear the active queries or load your saved work if you are
    inactive for more than 30 minutes, otherwise queries might be
    inaccurate. If the status gets stuck at "working" for a long time,
    you may come back to the page later.
</label>
```