Fail buildAboutPage task on error

No Issue
- If buildAboutPage encounters a problem, fail the task so
  the entire test suite doesn't run only to fail because the
  template partial is missing.
- Cleaned up task.
Adjust about page tests

No Issue
- Wait for list item element to appear before starting tests
  to make sure template partial has been rendered.
- Remove test for 20 list items as it's possible that there
  could be fewer than 20 contributors for during the window.
  Instead just test to make sure the list has at least one item.
Merge pull request #4718 from jaswilli/about-tests

Adjust about page tests
Merge pull request #4717 from jaswilli/about-task

Fail buildAboutPage task on error
Make embedded-record-adapter the default

No Issue
- Generalize embedded-record-adapter so it can be used
  for both fetching and saving records.
- Change Adapter inheritance heirarchy to
  RESTAdapter => BaseAdapter => EmbeddedRecordAdapter. ApplicationAdapter
  now extends EmbeddedRecordAdapter.
- Cleanup or remove adapters that existed just to extend directly
  from EmbeddedRecordAdapter.