Refactor storage system

[kaosat-dev]

Right now it is full of hacks, dirty and unwieldy:
Some thoughts on the necessary improvements:

• seperate stores (high level api) from file systems (low level file and folder manipulation)
• stores should be able to use any number of fs (ie for example cache remote data in local storage etc)
• stores and /or fs need to be part of the kernel, not the ui/app (view independant)
• the way fs interact with the pre processor (kernel) needs to be reviewed : must NOT depend on any backbone marionnete application level communications : ideally a simple array of available stores/fs could be passed in to the preprocessor (this has been tested , seems to work fine, but code not yet migrated)

Following stores/fs are needed:

• dropbox (clean up of current): add caching to local storage
• browser/local storage (cleanup of current)
• ajax fs : retrieve files (read only) by url
• node fs : needed for desktop app (node-webkit)
• couch db ? see with Simon Kirkby