Add content history to banners, including banner categories and banner
clients.
Merge branch 'master' into history-banners

Conflicts:
	installation/sql/mysql/joomla.sql
Merge branch 'master' into history-banners
Fix update SQL script.
Remove duplicate code for banners content types in update.
Merge branch 'master' into history-banners
Merge master
Merge branch 'master' of https://github.com/joomla/joomla-cms into history-banners

Conflicts:
	administrator/components/com_banners/models/forms/client.xml
	administrator/components/com_banners/views/banner/tmpl/edit.php
	administrator/language/en-GB/en-GB.com_banners.ini
Merge pull request #2177 from elinw/history-banners

History banners