deposit: js uploader component

* Adds flightjs uploader component with support for pluggable
  uploader engines such as PLUpload and DropBox.

* NOTE RequireJS path to FlightJS was changed from vendors/flight/lib
  to vendors/flight. Scripts defining flight components MUST update
  their require statement from require('flight/lib/component') to
  require('flight/component').

Reviewed-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
Signed-off-by: Adrian Pawel Baran <adrian.pawel.baran@cern.ch>