Merge branch 'stable-2.8' into stable-2.9

Merge branch 'stable-2.8' into stable-2.9

* stable-2.8
  Add a default to file-driver when unspecified over RAPI
  Remove typo from RAPI documentation
  Describe the files in doc/users in NEWS
  Update the upgrade procedure

* stable-2.7
  Fix incorrect manpage reference to htools

Conflicts:
	NEWS
	configure.ac
	lib/cmdlib/instance.py
	man/hroller.rst

All trivial, except for man/hrooler.rst, where the
fix in the section number was manually applied to the
new text.

Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Thomas Thrainer <thomasth@google.com>