Add tests from the old svn tree

We're losing the svn history (which we could probably keep if we tried
hard enough) but don't consider that worthwhile.

Note these tests are destructive, so run them only in a throwaway
environment like a chroot, container, or vm.

The tests/run.all script should be the one which launches all the tests.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

tests/grouptools/groupadd/22_groupadd_usage/data/usage.out

@@ -0,0 +1,14 @@
+Usage: groupadd [options] GROUP
+
+Options:
+  -f, --force                   exit successfully if the group already exists,
+                                and cancel -g if the GID is already used
+  -g, --gid GID                 use GID for the new group
+  -h, --help                    display this help message and exit
+  -K, --key KEY=VALUE           override /etc/login.defs defaults
+  -o, --non-unique              allow to create groups with duplicate
+                                (non-unique) GID
+  -p, --password PASSWORD       use this encrypted password for the new group
+  -r, --system                  create a system account
+  -R, --root CHROOT_DIR         directory to chroot into
+