Dismiss Keyguard Util

Devices running Froyo and Gingerbread always shows the keyguard even when the setting is
configured to disable it.

This utility listens for com.android.tradefed.utils.DISMISS_KEYGUARD intent then
create a service to disable the keyguard without the need for root access.

Change-Id: I453c8cd8005700eb6008d15e7c6d073681375850