Added some useful information to image upload resp

* Refactored the controller. Placed all the upload logic inside a new service
* Changed the tests to make it happen
* Changed the default field name of image to "file". Previously was "image"
* Added some useful (and elcodi related) response data in the upload response
    * resize route wildcarded
    * view route wildcarded
By default, the name of the field in html is "file", so this change turns our implementation more normalized.