Signup modal

Just translate discussion sr text

Markdown editor help

Help modal and reverify dash

Changed "Status Page" -> "Page".

UX:
    support for displaying built-in tabs
    restored drag and drop on Studio Pages
    additional styling for fixed state on Studio Pages
    add a new page action added to bottom of Studio Pages

Dev
    changes for viewing tabs in studio,
    refactored the tab code,
    decoupled the code from django layer.
    is_hideable flag on tabs
    get_discussion method is needed to continue to support
external_discussion links for now since used by 6.00x course.
    override the __eq__ operator to support comparing with
dict-type tabs.

Test
    moved test code to common,
    added acceptance test for built-in pages
    added additional unit tests for tabs.
    changed test_split_modulestore test to support serializing objects
that are fields in a Course.

Env:
    updated environment configuration settings so they are
    consistent for both cms and lms.

Introduction of the Microsite feature which allows for limited multi-tenant branding on a subdomain basis, e.g. foo.edx.org and bar.edx.org

fix errorenous logic when running a microsite that could reside in a hosting environment with a marketing site in front of it

pep8/pylint fixes

address PR feedback, remove underscore from test hostname

more pep8/pylint cleanup. Skip test_microsites test, it works on localdev, not on Jenkins. Need to talk with QA team

manually add Ned's single-to-double quote fix

change aws.py runtimes so that the microsite_dir that is read from configuration is changed to a python path

Conflicts:
	lms/templates/help_modal.html

[LMS-1680]

Users should be able to close the modal with the "escape" key.

Modal dialogs should manage keyboard focus, ensuring that users can't
tab out of the modal dialog and back into the page itself (effectively
moving “behind” the dimmed modal). On the last focusable element of the
dialog, return focus back to the first focusable element.

Also move the close button to the start of the dialog's section, making
it the first focusable URL, to ensure focus matches the visual
representation of the dialog.

The close button for the modal dialog was marked up as a paragraph,
containing a graphical text character, inside two div elements, with an
associated click event. This made the button unusable for keyboard
users.

Replaced <divs> with a link element (<a role="button"), adapted the CSS
accordingly, and updated the existing <a> modal close buttons.

Added a 'aria-hidden="true"' attribute to the modal initially, then
toggle the value of that attribute to "false" when the modal is shown.
Also remove the attribute when the modal is closed, whether it's through
a click on the close button or on the overlay.

> To make this change explicit to assistive technology, focus should be
> moved programmatically to this div after it has been made visible. To
> allow the div to be focused via scripting (without adding it to the
> regular focus order that keyboard users cycle through), a tabindex=”-1”
> should be added.

> In addition, the invalid fields should be given a an
> aria-invalid="true" attribute.

syntax fix

fixes template errors

keep tos untranslated

formatting fixes

Accidentally got removed in pull request 13.

As per request from Mary.