Add DJFS settings (OSPR-50)

Add DJFS settings (OSPR-50)
To solve this pr:
https://github.com/edx/edx-platform/pull/5291
Merge pull request #1635 from fmyzjs/patch-1

Add DJFS settings (OSPR-50)
Add sane defaults for djfs.
Merge pull request #1674 from edx/feanil/djfs_defaults

Add sane defaults for djfs.
Update to use the stable ppa for datadog.

Remove the old repository.

Explicitly control the version of Datadog.
Merge pull request #1676 from edx/feanil/update_datadog_agent

Feanil/update datadog agent
quick fix to issue-certificate
Merge pull request #17 from edx/master

Try to merge  Master@2014.11.1