Add Power Usage Page

Created a new page, "Manage Power Usage".
This page is under the "Server control" tab.
This new page currently just displays the power consumption.
Future commits will allow the user to set the power cap from
this page. One day, things like power consumption trending
data could also be on this page.

There was a blank unused controller which was for similar things,
removed it.

Tested: See the page and the consumption data. Uploaded screenshots
        to openbmc/openbmc#3221
Change-Id: I9f97c58a086f34c1c1990c03d5e05b081619bd5c
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/app/index.js b/app/index.js
index e385ecd..4d9ed64 100644
--- a/app/index.js
+++ b/app/index.js
@@ -59,6 +59,7 @@
 import server_control_index from './server-control/index.js';
 import bmc_reboot_controller from './server-control/controllers/bmc-reboot-controller.js';
 import power_operations_controller from './server-control/controllers/power-operations-controller.js';
+import power_usage_controller from './server-control/controllers/power-usage-controller.js';
 import remote_console_controller from './server-control/controllers/remote-console-controller.js';
 import remote_console_window_controller from './server-control/controllers/remote-console-window-controller.js';
 import server_led_controller from './server-control/controllers/server-led-controller.js';
@@ -67,7 +68,6 @@
 import inventory_controller from './server-health/controllers/inventory-controller.js';
 import inventory_overview_controller from './server-health/controllers/inventory-overview-controller.js';
 import log_controller from './server-health/controllers/log-controller.js';
-import power_consumption_controller from './server-health/controllers/power-consumption-controller.js';
 import sensors_controller from './server-health/controllers/sensors-controller.js';
 import sensors_overview_controller from './server-health/controllers/sensors-overview-controller.js';