Find the courses a user has certs for up front.

Before this commit, we had to do a separate query for every course a
user was enrolled in when determining whether a course was refundable
(if you have a certificate, it isn't). Now the student dashboard will
make a one-time query to grab all of a user's cert-issued courses. This
is indexed, so it should be much faster than grabbing each one
separately.

ECOM-7099

ECOM-7099

Storage-backed versioned Block Structures: Config

Student Dashboard CourseOverviews with one query.

Pre-load the course overviews attached to CourseEnrollments on the
Student Dashboard, if possible. This will only grab the CourseOverviews
that already exist, and will not generate new ones. Any missing
CourseOverviews fall back to the lazily-created one-at-a-time behavior
they've always had. That's mostly because I wanted to optimize for the
common case in the least invasive way possible, and I don't want to get
caught up in locking issues.

Update translations (autogenerated message)

Select related users when returning enrollments.

Test Speedup: Isolate Modulestore Signals

There are a number of Django Signals that are on the modulestore's
SignalHandler class, such as SignalHandler.course_published. These
signals can trigger very expensive processes to occur, such as course
overview or block structures generation. Most of the time, the test
author doesn't care about these side-effects.

This commit does a few things:

* Converts the signals on SignalHandler to be instances of a new
  SwitchedSignal class, that allows signal sending to be disabled.

* Creates a SignalIsolationMixin helper similar in spirit to the
  CacheIsolationMixin, and adds it to the ModuleStoreIsolationMixin
  (and thus to ModuleStoreTestCase and SharedModuleStoreTestCase).

* Converts our various tests to use this new mechanism. In some cases,
  this means adjusting query counts downwards because they no longer
  have to account for publishing listener actions.

Modulestore generated signals are now muted by default during test runs.
Calls to send() them will result in no-ops. You can choose to enable
specific signals for a given subclass of ModuleStoreTestCase or
SharedModuleStoreTestCase by specifying an ENABLED_SIGNALS class
attribute, like the following example:

    from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase

    class MyPublishTestCase(ModuleStoreTestCase):
        ENABLED_SIGNALS = ['course_published', 'pre_publish']

You should take great care when disabling signals outside of a
ModuleStoreTestCase or SharedModuleStoreTestCase, since they can leak
out into other tests. Be sure to always clean up, and never disable
signals outside of testing. Because signals are essentially process
globals, it can have a lot of unpleasant side-effects if we start
mucking around with them during live requests.

Overall, this change has cut the total test execution time for
edx-platform by a bit over a third, though we still spend a lot in
pre-test setup during our test builds.

[PERF-413]

Prevent OpenBLAS from spawning worker threads. TNL-6456

Fix posts are not automatically followed

remove space around xsy avatar image

bump edx-sga XBlock to v0.6.2

Adding text param to webob response for 1.7.1. 

use PyPI version of edx-sga and move to base.txt

Moving upgraded e2e page objects to platform

ENT-228: Allow tpa_hint to match hidden providers

The RLIMIT_NPROC limit is per-user so simultaneous student submissions
pile up and overflow the limit.  Setting this environment variable will
prevent spawning any threads (the 1 means only have one threads, the
already existing main thread).

Short-term fix for TNL-6559 task failures

moving tabindex

ECOM-7098

Merge release back to master

reset grades management command choose database table

TNL-6553

WL-977 | Set 'created_on_site' UserAttribute on account creation

We need to be able to track which site a given user account was created on. This
change will create a UserAttribute model with a key of 'created_on_site' and a value
containing the domain of the site on which the user accounted was created.

WL-977

Update embargo message with better language ECOM-7119

Utilize scrapy parse

specify custom callback and add port

Getting rid of scrapy parse. A modified crawl will work

remove log

Remove unnecessary input options

Remove extra empty line

version bump v1.5.9

Reduce duplicate code

add in port and simplify further

clean command further

add port to basic command

Bump Pa11yversion to the newest version

TNL-6553

Fix lettuce tests for Xenial compatibility and newer Chrome version.