As described in https://wiki.php.net/vcs/gitworkflow#the_news_file it is possible to setup a custom merge driver for NEWS so git doesnt try to merge it. This commit sets the default merge driver for the NEWS file to the merge driver called NEWS.
We usually don't want to touch the NEWS files when we merge and have the news items not merged by git. Therefore we tell git to use the 'ours' strategy for the NEWS file.
Git supports a limited $Id$ keyword expansion. This $Id$ tag is similar to $Revision$ in SVN. We enable the $Id$ expansion only for files that use $Revision$.