[LEARNER-168]

The course and program dashboards interpret an empty upgrade deadline to mean that a given seat is available. Previously, program dashboard pages interpreted empty upgrade deadlines to mean that a given seat was not available.

LEARNER-935

LEARNER-382

The read_cached_programs switch was used to control the release of changes for reading programs exclusively from the cache. With those changes stable, the switch is no longer necessary.

LEARNER-382

* Reorders form fields, and updates labels, placeholders, and tip text
* Increases clickable area for links and labels.
* Removes "*" markers from required fields, and instead adds
  "(optional)" labels to visible optional fields.
* Updates font colors and sizes, and removes box shadows
* Adds custom drop-down styles
* Improves responsive design scaling for small screens
* Make Terms of Service and Honor Code open in new window to avoid losing form
  field values.

This reverts commit 5388d5d1.

LEARNER-879

Generator expressions passed to the memcached backend's implementation of get_many() are exhausted prematurely. This results in KeyErrors when the backend tries to map keys returned by memcached back to keys passed by application code.

See https://github.com/django/django/blob/stable/1.8.x/django/core/cache/backends/memcached.py/#L99.

LEARNER-382

This reverts commit 16e96365.

When enabled, these changes prevent LMS application code from hitting the discovery service in-process to retrieve programs. Instead, program data is pulled from cache entries populated by a management command, cache_programs.

LEARNER-382

This prevents the LMS from requesting details for programs which the command hasn't been able to cache yet, which would throw off monitoring we'll be setting up to keep an eye on missing entries.

LEARNER-382

LEARNER-764

EDU-218

Also add it to the course home page.

This command requests every available program from the discovery service, writing each to its own cache entry with an indefinite expiration. It is meant to be run on a scheduled basis and should be the only code updating these cache entries.

LEARNER-382

LEARNER-609