realm: remove $gid = '500'

realm used to have the default $gid (set to 500, wikidev), as a global
variable. Since the admin module was introduced though, this should be
unused and grepping confirmed that.

Besides being superfluous, this breaks puppet runs with a newer facter,
as facter now comes with a "gid" fact that conflicts with this global
variable of ours.

Also remove a $gid assignment for ocg hosts under site.pp, that had a
comment "what is this used for?" :)

Change-Id: Ibb2c5fe6a194d145f6be11105323d2f6f4bafe8a
os_version/requires_os: drop support for variadic args

a) We're not using them, b) supporting them means we may get
inconsistence use across the tree, c) it's currently broken and fixing
it doesn't seem like worth the trouble.

Change-Id: Ib36d242c521620fd94b061315e28457987d189a1