* 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
* PLT-5319 - Fixing text alignment security modal
* PLT-5280 - Fixing add comment button in RHS mobile
* PLT-5397 - Fixing Floating timestamp on mobile
* PLT-5129 - Hiding formatting help text
* PLT-5242 - Adjusting team sidebar border on IE!!
* PLT-5226 - Placing settings toggle over header
* PLT-5222 - Placed team description tooltip on top
* PLT-5201 - Account settings overlap on mobile
* PLT-5138 - Adding bg to pending post actions
* PLT-5286 - Adjusting play button on youtube videos
* PLT-5313 - Adjusting space between emoji reactions
* PLT-5187 - Adjusting text in channel switcher
* PLT-5399 - Reverting button alignment in modal
* PLT-5090 - Adding overflow for usrename on popover
* PLT-5089 - Updatng save button position
* PLT-5146 - Removing anchor on teamname/username
* Minor fixes for profile popover
* Adjusting constants call for sidebar header
* Cleaned up user_settings_theme.jsx and import_theme_modal.jsx
* Made ImportThemeModal use a callback to return the theme to the user settings modal instead of saving it directly
* Moved user theme from model to preferences
* Added serverside API to delete preferences TODO update package with client stuff
* Changed constants.jsx so that Preferences and ActionTypes can be imported on their own
* Updated ThemeProps migration code to properly rename solarized code themes
* Fixed warnings thrown by AppDispatcher
* Added clientside UI to support team-specific themes
* Removed debugging code from test
* Fixed setting a user's theme when they haven't set their theme before
