Eliminate the required_email module!

* Make the authenticate handle everything.

fixes #1873
Remove the remnants of the old requiredEmail module

fixes #1873
Cleanup, 'cause as @6a68 says, my class names sucked.

* isRequiredEmail=>isEmailImmutable
* requiredEmail=>emailImmutable
* isNotRequiredEmail=>isEmailMutable

Other changes
* Remove the "#back" and "#required_email" CSS, elements with these ids are nowhere to be found in any template.
* Use high level "testElementHasClass" and "testElementNotHasClass" tests instead of low level equivalents.
Update the selector for forgotPassword.
Merge pull request #3630 from shane-tomlinson/refactor_eliminate_required_email

Refactor eliminate required email

@6a68 gave the r+, I cleaned up the class names. merging. Thanks for the collaboration @6a68!
Get rid of the "<IdP> makes this easy!" screen

* Cleanup of the verify_primary_user module to remove global state.
* Add module.js->importFrom
* update the Selenium for the removal of the '<IdP> makes this easygit add .' screen

fixes #3671
Merge pull request #3680 from mozilla/issue_3671_remove_makes_it_easy

Issue 3671 remove makes it easy
Copy shortening and authentication page title simplifications.

* Integrate @ryanfeeley's suggested copy changes.
* Simplify the way the title is displayed on the authentication page. Instead of using JS to display the appropriate title, use CSS.
Clean up the text for transition_to_primary
Fix the failing front end tests

* A .description element no longer exists
* Move the #upgrade_to_primary id to what used to be the .description element.
Merge pull request #3684 from mozilla/issue_3609-dialog_copy

Copy shortening and authentication page title simplifications.

I rebased and can now merge cleanly. Thanks @seanmonstar for reviewing!

merging.
Check for failures in provisioning after returning from an IdP.

* This is a standin for checking for disabled 3rd party cookies. If we expect
provisioning to succeed, but it fails, this is probably due to disabled 3rd party cookies.

fixes #3520
Update text with @ryanfeeley's suggestions.

Thanks @ryanfeeley!
Update with @seanmonstar's suggestions for escaping.
Merge pull request #3690 from mozilla/issue_3520-3p_cookies_disabled

Check for failures in provisioning after returning from an IdP.
Move context request from xhr.js to network.js
Clean up

Get rid of duplicate state held in top level variables and within context.
publish context_info with the full updated context, not just the passed in context.
Add is* functions to helpers, use isObject to ensure setContext is called with valid parameters.

* add isArray, isFunction, isObject, isString
Clear all timeouts between tests to prevent cross-test pollution.