Remove some potentially objectionable server names

Some of the server names (derived from DotA characters) have violent
or occult connotations, or are otherwise undesirable as a first
impression of Rethink. 21 of these names have been removed, leaving
84 (which should be enough for most clusters).

Fixes issue #2464 (though a better solution for server naming may be
desired in the future, see issue #236).