Factor out env/option pattern into config().envOrGet(<option>)
File extension option for Coffee/Iced compiler task
Optionally generate source maps in build/map/Resources

This is where Alloy also places source maps:
https://github.com/appcelerator/titanium-code-processor/blob/8cdc855adb8a2217de70e04cdc44941cd6f254f6/commands/analyze.js#L573
Custom WatchTask -- neither `coffee --watch` nor jake.WatchTask have required functionality
`invoke` keyword for jake/tintan api