Refactor existing code

Most of the code already exists, but :

• API may not be as good as we would like
• it is splited in several files (automation.js, dnd-upload ...)
• see if we keep jQuery as a requirement
• see if we provide an encapsulation for async calls (Deferred ?)

The goal is to have a single library that can handle at least :

• automation RCP calls
• batch API calls
• uploads pool

NB : on recent browsers, we should also be able to leverage the "standard" blob API based on multi-part encoding.