If disk name has '.', replace with '_'

graphite uses . as the separator between different metric parts

see cloudron/box#348

src/views/system.js

@@ -77,9 +77,9 @@ angular.module('Application').controller('SystemController', ['$scope', '$locati
                 // render data of each disk
                 async.eachSeries(result.disks, function (disk, iteratorCallback) {
                     // /dev/sda1 -> sda1
-                    // /dev/mapper/foo -> mapper_foo (see #348)
+                    // /dev/mapper/foo.com -> mapper_foo_com (see #348)
                     var diskName = disk.filesystem.slice(disk.filesystem.indexOf('/', 1) + 1);
-                    diskName = diskName.replace(/\//g, '_');
+                    diskName = diskName.replace(/\/|\./g, '_');
 
                     // use collectd instead of df data so the timeframe matches with the du data
                     Client.graphs([