drop support for 'retainData' configuration

storage/file.js

@@ -555,9 +555,6 @@ var listChannels = function (root, handler, cb) {
 // to an equivalent location in the cold storage directory
 var archiveChannel = function (env, channelName, cb) {
     // TODO close channels before archiving them?
-    if (!env.retainData) {
-        return void cb("ARCHIVES_DISABLED");
-    }
 
     // ctime is the most reliable indicator of when a file was archived
     // because it is used to indicate changes to the files metadata
@@ -875,7 +872,6 @@ module.exports.create = function (conf, cb) {
     var env = {
         root: conf.filePath || './datastore',
         archiveRoot: conf.archivePath || './data/archive',
-        retainData: conf.retainData,
         channels: { },
         channelExpirationMs: conf.channelExpirationMs || 30000,
         verbose: conf.verbose,

storage/tasks.js

@@ -202,22 +202,6 @@ var expire = function (env, task, cb) {
     var Log = env.log;
     var args = task.slice(2);
 
-    if (!env.retainData) {
-        Log.info('DELETION_SCHEDULED_EXPIRATION', {
-            task: task,
-        });
-        env.store.removeChannel(args[0], function (err) {
-            if (err) {
-                Log.error('DELETION_SCHEDULED_EXPIRATION_ERROR', {
-                    task: task,
-                    error: err,
-                });
-            }
-            cb();
-        });
-        return;
-    }
-
     Log.info('ARCHIVAL_SCHEDULED_EXPIRATION', {
         task: task,
     });
@@ -381,7 +365,6 @@ Tasks.create = function (config, cb) {
         root: config.taskPath || './tasks',
         log: config.log,
         store: config.store,
-        retainData: Boolean(config.retainData),
     };
 
     // make sure the path exists...