This allows mattermost to use a non-tls connection with a SMTP server that
supports PLAIN auth (but not LOGIN). The go library explicitly allows PLAIN
auth over non-tls connections - https://golang.org/src/net/smtp/auth.go#L55Fixes#2929
* PLT-3647 Added config settings for email batching
* PLT-3647 Refactored generation of email notification
* PLT-3647 Added serverside code for email batching
* PLT-3647 Updated settings UI to enable email batching
* PLT-3647 Removed debug code
* PLT-3647 Fixed 0-padding of minutes in batched notification
* PLT-3647 Updated clientside UI for when email batching is disabled
* Go fmt
* PLT-3647 Changed email batching to be disabled by default
* Updated batched email message
* Added email batching toggle to system console
* Changed Email Notifications > Immediate setting to a 30 second batch interval
* Go fmt
* Fixed link to Mattermost icon in batched email notification
* Updated users to use 30 second email batching by default
* Fully disabled email batching when clustering is enabled
* Fixed email batching setting in the system console
* Fixed casing of 'Send Email notifications' -> 'Send email notifications'
* Updating UI Improvements for email batching (#3736)
* Updated text for notification settings and SiteURL.
* Prevented enabling email batching when SiteURL isn't set in the system console
* Re-added a couple debug messages
* Added warning text when clustering is enabled
* PLT-3484 OAuth2 Service Provider
* PM text review for OAuth 2.0 Service Provider
* PLT-3484 OAuth2 Service Provider UI tweaks (#3668)
* Tweaks to help text
* Pushing OAuth improvements (#3680)
* Re-arrange System Console for OAuth 2.0 Provider
* EE: Add Google and Office365 SSO through OAuth2
* Add localization strings
* Text tweaks for PLT-3633
* Added sign-up button for Office 365
* Updated some error messages and a bit of licensing
* Updated sign-in method section in user settings to include Google and Office365
* Added more localization strings
* PLT-1866 Added configurable links for native app downloads
* PLT-1866 Added native app download link to main menu
* PLT-3509 Added native app link to tutorial
* PLT-3509 Added native app link to welcome email
* PLT-3509 Made link to apps in welcome email conditional on being set
