Added email sending endpoint to the API.
closes #2550

- Added new API module named 'mail'
- Added routes for the mail endpoint
- Added 'send a test email' button to the debug settigns page
- Added handler to this button which sends and AJAX request to the mail API endpoint
Do not redirect to editor if parameter does not equal edit.

Closes #2619
- If edit parameter is 'edit' redirect to editor.
- If edit parameter is anything other then undefined redirect to 404.
- Create edit post tests.
- Test redirect without trailing slash.
- Test redirect to editor.
- Test redirect to 404.
Tag API: Primary Document Format

Closes #2605

- Change tags browse() response to { tags: [...] }
- Update client side collection to use nested tags document
- Update test references to use response.tags
Merge pull request #2626 from jgable/apiTagPrimaryDocument

Tag API: Primary Document Format
Merge pull request #2551 from szelpe/email-test

[API] Added email sending endpoint to the API.
Merge pull request #2624 from shindakun/editbug2619

Do not redirect to editor if parameter does not equal edit.