Escape text on hidden content dividers.

ReviewBoard shows you a certain amount of context around the changes.
Above
this you're provided with two options...

  [+] 1005 lines
  [+] public void titlesModified(List<Title> titlesAdd, List<String>
      titlesDelete,

This is all fine and well, except in the case of content like that shown
above.  'Title' coincidently belongs to an html tag, and including it
breaks the html parser for the page (as it would with '</script>' and a
few other things). HTML escaping these lines to prevent this.

The main visible result is that diff hunks beyond the first fail to
load. In firebug you get the error of...

Uncaught ReferenceError: setFileAttachmentComments is not defined

Reviewed at http://reviews.reviewboard.org/r/4330/
Fixes bug #2612
Merge branch 'release-1.6.x' into release-1.7.x
Update Amazon S3 support to use the newer django-storages s3boto backend.

It seems that the Amazon S3 support for file storage is broken. It is
likely that this is due to the changes in Amazon side. Right now the
default AWS SDK for Python is boto which is already supported by
django-storages. it only requires to specify a different backend.

This will add a new dependency to reviewboard in order to support
Amazon S3. Apart from django-storages, boto package is also required.

Note: I needed to uninstall the botocore package which was also
installed in my system. It seems there was a conflict with boto.

Reviewed at http://reviews.reviewboard.org/r/4333/