Merge branch 'stable-2.2'

* stable-2.2:
  Release 2.2.1~rc1
  Require aclocal 1.11.1 or above for devel/release
  Revert "Require aclocal 1.11.1 or above for autogen.sh"
  Add mising --units in gnt-instance list man page
  Set list of trusted SSL CAs for client to verify
  Require aclocal 1.11.1 or above for autogen.sh

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>