improve error reporting for reload_forum_users cmd

If this management command fails it's tough to figure out why without
seeing the text from the exception.  Luckily comment service does
return useful feedback, we just have to show it.  This one-line
change just add the exception text to the error message.

Before (with spurrious debug msgs removed):

    sefk@util1:~$ ./manage.sh reload_forum_users Anthonyhubendurance
    update user info to discussion failed for user with id: Anthonyhubendurance

After:

    sefk@util1:~$ ./manage.sh reload_forum_users Anthonyhubendurance
    update user info to discussion failed for user with id: Anthonyhubendurance, error=u'["Email is already taken"]'

No unit testing (sorry) added since this doesn't have coverage
already, and it's just a simple error case.
Change the from address for LinkedIn emails
Merge pull request #2363 from edx/sef/forum_reload_errmsg

improve error reporting for reload_forum_users cmd (one-liner)
Merge pull request #2371 from edx/diana/linkedin-from

Change the from address for LinkedIn emails
Note to Instructors on Regular & Beta Dashboard

- Added note to instructors on Forum Admin page of Instructor Dashboard.
- Made Role Info divs permanently displayed, but under the user list.
/register_post is an invalid URL
Merge pull request #2376 from edx/db/fix-studio-signup-form-action

/register_post is an invalid URL
Force unique course_id for bulk email authorization

LMS-2134
Merge pull request #2373 from edx/sarina/fix-course-authorization

Force unique course_id for bulk email authorization
Merge pull request #2245 from edx/giulio/instructor-forum-role-info

Note to Instructors on Regular & Beta Dashboard