Branch: master

      Fixed few bugs related to Javascript on Mboard page occurring while
      trying to post a message to an existing dialogue.

============= Updated
    /app/views/users/_list_users.html.haml
      - Moved the code
          = hidden_field_tag "user_id", user.id
        to  /app/views/users/_list_dialogues_name.html.haml

        When the following SPAN's
          %span{ id: "dialoguesListing_#{user.id}" }
        content was getting updated dynamically from server response the
        INPUT HIDDEN field (#user_id) was getting removed due to which selecting
        a dialogue was not opening up the user's message box.

    /app/controllers/messages_controller.rb
      - Updated implementation in method: create.
        In case @message.message_thread.nil? is true checking if MessageThread
        with a same name exists? If yes then posting the message to that MessageThread
        else creating a new one.

    /app/views/messages/message_status.js.haml
      - While starting a new dialogue if a message thread by specified title
        already existed, then informing user about the same in the status message.