Add type button so it doesn't resubmit form

Author: Nick Litwin

app/submissions/submit-file/submit-file.jade

@@ -110,7 +110,7 @@
 
             tc-input.fieldset__input(label-text="File Number", placeholder="u2434312", input-value="stockArt.fileNumber")
 
-          button.fieldset__button.tc-btn.tc-btn-s(ng-click="vm.createAnotherStockArtFieldset()") + Add Stock Photo
+          button.fieldset__button.tc-btn.tc-btn-s(type="button", ng-click="vm.createAnotherStockArtFieldset()") + Add Stock Photo
 
     .panel-footer
       p Submitting your files means you hereby agree to the #[a(href="https://www.{{DOMAIN}}/community/how-it-works/terms/", target="_blank") Topcoder terms of use] and to the extent your uploaded file wins a Topcoder Competition, you hereby assign, grant, and transfer to Topcoder all rights in and title to the Winning Submission (as further described in the terms of use).