Schedule Roadmap/M2.5/MediaStorageAPI

Feature Requirements

• Prototype the ability to save "Blob" files into well-known device storage. On b2g, this would be /sdcard/[somewhere].
• We also need to allow querying the storage from privileged apps. (This work can be prototyped entirely in the b2g chrome package.)
• We can skip some of the stringent security checks for the developer preview