Reportback modal

* Opens modal after user uploads a file
* First pass at modal styles
* Allows user to enter a caption

@weerd @DFurnes 
@DFurnes Yea maybe. After we talking in the fender meeting yesterday and I realized mocks can be off from the neue patterns, some of these styling decisions will need to be revisited. The button in the mock was way smaller thant what a primary button looked like, but it was blue and it is also the only button in the modal.