Restore reverted changes from paver part 1

This reverts commit df2e410f.

Deprecated rake functions issue a warning and then call paver
replacements

Bring Paver commands up to date with master for servers, assets, and docs.
Revert deprecation of quality, tests, and i18n for a future pull request.
Deprecate workspace migration

To acknowledge his help with refactoring URLs in our CSS to be
protocol-relative

This reverts commit 540256b2, reversing
changes made to bd04ab5a.

Signed-off-by:  <manuel.freire@fdi.ucm.es>

Adds a code block to the problem markdown parser that translates
[code]
TestTest
[/code]
to
<pre><code>
TestTest
</code></pre>

Usefull variables for translation

Adds a new Email link to the instructor dashboard for frontend interface to send
email to course members. Adds a feature flag ENABLE_INSTRUCTOR_EMAIL to toggle this.
Creates a new djangoapp bulk_email that handles this action by getting the recipient
list and batching the emails to different celery tasks to do the actual sending.
Requires lynx package to convert HTML email to plaintext. Handles SMTP errors by
retrying or falling through to the next email. Adds the option to opt out of course
specific emails in the user dashboard with an Email Settings link for each course.
Uses severable configurable settings with defaults. DEFAULT_BULK_FROM_EMAIL
specifies the from address for email. EMAILS_PER_TASK specifies the number of emails
each celery task takes on. EMAIL_HOST, EMAIL_PORT, EMAIL_HOST_USER,
EMAIL_HOST_PASSWORD, and EMAIL_USE_TLS for the SMTP email backend settings.

Co-authored-by: Akshay Jagadeesh <akjags@gmail.com>

vagrant:
  - check actual IP;
  - only init machine first time, just as native installations;
  - add .bash_profile to permissions fixup;
  - cleanup excessive newlines in making .bash_profile;

README:
  - include admin & debugging use;
  - info about re-initializing VM & manually running create-dev-env.sh;
  - add django admin & debug_toolbar setting info

Conflicts:
	AUTHORS
	scripts/vagrant-provisioning.sh