gpg: Change armor Version header to emit only the major version.

* g10/options.h (opt): Rename field no_version to emit_version.
* g10/gpg.c (main): Init opt.emit_vesion to 1.  Change --emit-version
to bump up opt.emit_version.
* g10/armor.c (armor_filter): Implement different --emit-version
values.
--

GnuPG-bug-id: 1572
Signed-off-by: Werner Koch <wk@gnupg.org>
(cherry picked from commit e951782e937ce290be0d89d83e84b3daea997587)

Resolved conflicts:
	NEWS
	g10/armor.c
	g10/gpg.c