Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
Adding another tab to the "create exam" page in order to separate out the XML and HTML edit panes
Single-user completion certificate generation

* CourseCertificate model created
* Initial cert creation interface through manage.py for one-off cert
  production, s3 upload and (optional) email notification
* UserProfile updates to reflect certificate attachment, move 'Change
  Info' buttons to top of page.
Merge branch 'master' of https://github.com/Stanford-Online/class2go into giulio-working-2
Strip command-line arguments to cert generation
Certificates additional user input error checking
Change certificate to statement of accomplishment

* Change the text of the User Profile page to reflect the fact that we
  don't give out certifications, we give out statements of
  accomplishment.
* Similar updates to manage.py command help.
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
Merge branch 'master' of https://github.com/Stanford-Online/class2go into giulio-working-2
Initial port timed exams
Certificate Asset downloader for cert deployment

* Downloads assets for statements of accomplishment from the release
  bucket using secure credentials and stores them on localhost for use
  in certificate generation.
install bits for generating certs (#1424)

for @jrbl. Currently only xhtml2pdf.
Removing the duplicate preview-tab id
more porting timed exams
manually do a interactive exercise request (#2045)
added user information to paste into email when making a bug report
fixing Due Date side nav table spacing
Minimal UI for new cert creation

* Adds ./manage.py target, create_certificate, which lets you establish
  the database relationship signifying the existence of a particular
  kind of statement of accomplishment.
added clear question button
Cosmetic improvements to user profile page

* Cosmetic improvements to presentation of statements of accomplishment
  on user profile page.
* Introduction of new template utility filter, uscore2space, which
  converts underscores in the input string into spaces.