Country Label was causing confusions for learners if it was country of origin or in which they
are living so changed it to a more appropriate message.
LEARNER-174
Also updated some other error messages to some more appropriate error messages.

LEARNER-1858

LEARNER-1922

These new indices will allow for more efficient querying of schedules.

LEARNER-2222

date has passed

LEARNER-966

Learners can upgrade or enroll as verified in all remaining courses in a program from their programs dashboard

[LEARNER-1899]

LEARNER-2172

In the reset password flow one can enter a single character password and subsequently cannot login to the site as password complexity is apparently enforced on the login page. Login page should not enforce password complexity.

LEARNER-1209

This new property knows how to rely on schedule deadliens and fallback to course mode deadlines, when necessary.

This model will be used to control dynamic upgrade deadlines for
learners.

In Python 2.7, `__file__` returns `.pyc` by default, this breaks our
comparison so let's strip out the trailing `c`.

Input forms that need validation will have AJAX requests
performed to get validation decisions live.

All but a few important and common form fields perform
generic validation; these will need a back-end handler
in the future in order to have them validated through AJAX requests.

Information is conveyed on focus and blur for both
errors and successes.

In particular, implement a validation API for registration,
where a client makes AJAX calls to the endpoints requesting
validation decisions on each input. Responses are strings
dependent on the type of validation error; if no error,
then empty string to indicate OK.

LEARNER-2017

EDUCATOR-842: adds in management command to swap a course's xblocks from verified track cohorts to enrollment tracks

BlockStructures are stored in S3, but they're cached in memcached. Prior
to this commit, they were only written to memcached when first created.
This commit adds a write to repopulate the cache entry every time there
is a cache miss. Hopefully, this will help reduce the miss rate we're
seeing.

Template were using global TECH_SUPPORT_EMAIL for error pages. This
changes them to use the site email if there is one.

A site must be passed so the system knows which URL to use to contact
the Discovery Service.

LEARNER-1894

This commit adds in course messaging for three use cases. First,
when the user is not signed in, the user is shown a message that
provides a link to sign in or register. If the user is signed in
but not enrolled, they are given a link to do so. If the user is
enrolled but the course has not yet started, they are shown a
message explaining when the course starts and shown a link (not
yet enabled) to add a reminder to their calendar.

The implementation defines a base message class and extends it
for the course home messages as well as the previously implemented
page level messages.

LEARNER-1982

The site's configuration does not contain the API URL, it should not keep on displayed the old cached list of uuids.
LEARNER-1146

We have recently discovered that for any SSO Provider configured to skip
the registration form, we were auto checking the terms of service box,
which is a legal faux pas. Since IBM is planning to launch imminently and
is depending on this feature, we need to remedy this situation for enterprises
whose SSO Provider is configured to skip registration.

This PR hides all of the registration fields except TOS for this scenario
and disables the autoSubmit functionality that typically happens when skipping
registration.

https://openedx.atlassian.net/browse/EDUCATOR-891