As a user I would like to be able to disable autocomplete when running on battery

[bkyle]

When my computer is running on battery I would like to be able to disable autocomplete so that I can save power. This behaviour should be configurable so that users can decide whether they want to optimize for power efficiency or productivity.

• In order to preserve the first-run experience the extension should default to performing autocomplete regardless of power source.
• If autocomplete is disabled due to this behaviour it should be indicated in the status bar item.
• This behaviour should take precedent over whether a user has decided to pause autocomplete (see Keyboard Shortcut to Pause autocomplete? #13).
• If autocomplete is disabled due to this setting and the user manually pauses autocomplete, autocomplete should remain paused (for the duration of the session) after either disabling this setting or attaching the computer to a power source.