Add link to email chapter in advanced install
[bug #827649] l10n email templates for users and questions

* add the .ltxt domain so email template strings get extracted.

  this only affects jinja templates. the ones that are still
  django templates fail silently during extraction and never make
  it to the .pot file which is fine.

* convert users app and questions app emails from Django to Jinja
  with the exception of apps/users/templates/users/emails/pw_reset.ltxt
  because that template is rendered by Django's PasswordResetForm
  and thus it has to be a Django template until we change Kitsune
  so that jingo overrides the Django templating stuff.

* add required unsubscribe_text macro.

* fix question and answer model makers to create a user with a
  profile.

* create new sumo.email_utils library which simplifies dealing with
  email templates.

* fix all the places in the users and questions apps where we were
  rendering email templates using Django things to use Jingo things
  and use the correct locale.
[bug 804156] Mobile private messaging
mobile-new is the new mobile
Revert "Revert "[bug 825610] Add google-api-python-client to vendor.""

This reverts commit bb30e74a298271f2f9cff7119be913ccd163dc2a.
Revert "Revert "[bug 825610] Added python-gflags to vendor.""

This reverts commit b0493879994752d627fe7ffc5ff92b5ef3fa1e64.
Revert "Revert "[bug 825610] Add pyOpenSSL to compiled requirements.""

This reverts commit 603d15f9d507fee0b2584cd226d00e26b251f74f.
Revert "Revert "[bug 825610][bug 820930] Use Google Analytics for visitor KPI data.""

This reverts commit 8e58850b89da050d3ece6338a86b61d07cf87b43.
Revert "Revert "[bug 825609] Use Google Analytics for visits by locale data.""

This reverts commit d6331930f9505bd866e9c8b128a7b994ba3fd040.
Revert "Revert "[bug 825616] Use Google Analytics for document views.""

This reverts commit 2763cdee3c68347f1f0d179bcac909a77d627805.
Revert "Revert "Removed no longer used webtrends module.""

This reverts commit a81f82e7bcf060ce7a6c2d3cace28582c3f8aad2.
Revert "Revert "Properly indent mocked GA responses.""

This reverts commit 601d22816982268bda8435ae28d8e75b43dc664c.
Revert "Revert "Remove webtrends settings.""

This reverts commit 8f28ee260dec08c1eaaef9eed1dfcb202b520dd9.
Add local site-packages to PYTHONPATH.

To pick up the local version of PyOpenSSL.