* Created a new message indicator component to indicate new messages are present
outside the user's view:
* Created new component with styling
* Theming and i18n support for new messages indicator
* Count new unviewed messages and integrate with component
* Coding style for new message indicator
* Fixed bugs with new message indicator:
* Fix display issues with new message indicator
* Update text to deal with plurals in React
* Fix coded style for ticket 'PLT-1917': add new message indicator.
* Use only server generated timestamps for checking new messages at the bottom
* Move transitionend to prop, fix style selectors