Changes enableWakeLock => wakeLock.enabled to follow the pattern used by
other features and wakeLockEnabled => wakeLock. Also make the necessary
code changes to reference this new settings flags correctly.
Adds wake lock feature, which is available only for mobile users using
browser with support to the given API.
When an user using a supported device joins the meeting, a toast is
displayed offering to activate the feature.
Adds a toggle under settings menu to activate/deactivate it.
