Update covariate UI to use FTL macros wherever possible.
Add necessary js for ajax based file upload
Add view model for covariate upload ui
Use jquery.iframe-transport as fallback for file upload when FormData isnt available (<= ie9).
Extract generic BaseFileFormViewModel.
 Add some protection to the json parse in BaseFormViewModel (used to crash for 404s)
Add server side file upload capability.
Early merge protection
Merge pull request #188 from SEEG-Oxford/174-covariate-upload

Add support for file upload