Autotest: Update site remote power to use RPM Infrastructure

Updated site_host to include RPM power on, off, and cycle commands,
that implement the client side code of interacting with the RPM
Infrastructure.

Removed all the RPM specific classes from site_remote_power.py and
replaced them with one generic class that utilizes the new methods
in site_host.

Also updated hardreset in SerialHost to utilize these new methods
that it will inherit from site_host.

BUG=chromium-os:34664
TEST=Ran power_IdleServer against a machine in the lab.

Change-Id: I88627416ba001ecad08d96aea1e98d8073aef068
Reviewed-on: https://gerrit.chromium.org/gerrit/34001
Commit-Ready: Simran Basi <sbasi@chromium.org>
Reviewed-by: Simran Basi <sbasi@chromium.org>
Tested-by: Simran Basi <sbasi@chromium.org>
diff --git a/global_config.ini b/global_config.ini
index c33cccb..9232307 100644
--- a/global_config.ini
+++ b/global_config.ini
@@ -150,3 +150,4 @@
 # the "Sentry Switched CDU" type
 rpm_sentry_username: fake_user
 rpm_sentry_password: fake_password
+rpm_frontend_uri: http://chromeos-rpmserver1.cbf.corp.google.com:9999