zdtm: add tests which can be executed in a new user namespace (v2)

Sockets tests are excluded, because SO_RCVBUFFORCE and SO_SNDBUFFORCE
are protected by CAP_NET_ADMIN

tty*, pty* are excluded, because TIOCSLCKTRMIOS protected by
CAP_SYS_ADMIN

*ghost, *notify, *unlink* are excluded, because linkat(AT_EMPTY_PATH)
are protected by CAP_DAC_READ_SEARCH

v2: use a blacklist
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>