define all server intervals in a map so we can easily clear them all

lib/rpc.js

@@ -378,6 +378,7 @@ RPC.create = function (config, cb) {
 
     var Env = {
         historyKeeper: config.historyKeeper,
+        intervals: config.intervals || {},
         defaultStorageLimit: config.defaultStorageLimit,
         maxUploadSize: config.maxUploadSize || (20 * 1024 * 1024),
         Sessions: {},
@@ -388,7 +389,6 @@ RPC.create = function (config, cb) {
         evPinnedPadsReady: mkEvent(true),
         limits: {},
         admins: [],
-        sessionExpirationInterval: undefined,
         Log: Log,
         WARN: WARN,
         flushCache: config.flushCache,
@@ -427,7 +427,7 @@ RPC.create = function (config, cb) {
     };
     Quota.applyCustomLimits(Env);
     updateLimitDaily();
-    setInterval(updateLimitDaily, 24*3600*1000);
+    Env.intervals.dailyLimitUpdate = setInterval(updateLimitDaily, 24*3600*1000);
 
     Pinning.loadChannelPins(Env);
 
@@ -458,8 +458,7 @@ RPC.create = function (config, cb) {
             }
         });
         // expire old sessions once per minute
-        // XXX allow for graceful shutdown
-        Env.sessionExpirationInterval = setInterval(function () {
+        Env.intervals.sessionExpirationInterval = setInterval(function () {
             Core.expireSessions(Sessions);
         }, Core.SESSION_EXPIRATION_TIME);
     });