* Updating client dependancies. Switching to using yarn.
* Updating React
* Moving pure components to using function syntax (performance gains with newer react version)
* Updating client dependancies.
* Ignore .yarninstall
* Enabling pre-lockfile because it's the entire point of using yarn.
* Removing old webpack config
* Moving to new prop-types
* Fixing ESLint Errors
* Updating jest snapshots.
* Cleaning up package.json
* Implement server changes for group messaging
* Majority of client-side implementation
* Some server updates
* Added new React multiselect component
* Fix style issues
* Add custom renderer for options
* Fix model test
* Update ENTER functionality for multiselect control
* Remove buttons from multiselect UI control
* Updating group messaging UI (#5524)
* Move filter controls up a component level
* Scroll with arrow keys
* Updating mobile layout for multiselect (#5534)
* Fix race condition when backspacing quickly
* Hidden or new GMs show up for regular messages
* Add overriding of number remaining text
* Add UI filtering for team if config setting set
* Add icon to channel switcher and class prop to status icon
* Minor updates per feedback
* Improving group messaging UI (#5563)
* UX changes per feedback
* Update email for group messages
* UI fixes for group messaging (#5587)
* Fix missing localization string
* Add maximum users message when adding members to GM
* Fix input clearing on Android
* Updating group messaging UI (#5603)
* Updating UI for group messaging (#5604)
