anchor.diff:  % couch_plugins:install({"geocouch", "http://127.0.0.1:8000", "1.0.0", [{"R15B03", "+XOJP6GSzmuO2qKdnjO+mWckXVs="}]}).
   % couch_plugins:install({"geocouch", "http://people.apache.org/~jan/", "couchdb1.2.x_v0.3.0-11-gd83ba22", [{"R15B03", "ZetgdHj2bY2w37buulWVf3USOZs="}]}).
   
  --define(PLUGIN_DIR, "/tmp/couchdb_plugins").
  +plugin_dir() ->
  +  couch_config:get("couchdb", "plugin_dir").
   
   log(T) ->
     ?LOG_DEBUG("[couch_plugins] ~p ~n", [T]).
  
positive.code:       fun load_config_file/1,
        filelib:wildcard(
          filename:join(
            [?PLUGIN_DIR, get_file_slug(Name, Version),
             "priv", "default.d", "*.ini"]))).
  
  -spec load_config_file(string()) -> ok.
  
negative.code:   % gunzip
    log("unzipped"),
    TarData = zlib:gunzip(GzData),
    ok = filelib:ensure_dir(plugin_dir()),
    % untar
    erl_tar:extract({binary, TarData}, [{cwd, plugin_dir()}, keep_old_files]).
  
  
  % downloads a pluygin .tar.gz into a local plugins directory
  