adds new S3Widget that returns a File
 - ENDPOINT settings gets reinvented
 - adds URLWidget and FileWidget + test and travis-ci
 - removes filesystem operations
 - fixes $jQuery issue
 -- noConflict was used improperly and crashed all other jQuery code
 - bootstrap 3 support
 - adds support for content-type specification
 -- The destination tuple accepts a new third argument in form of a list. The list contains of MIMEType strings including wildcard options. It will not only be set to file input as the accepted attribute, but checked in the policy view.