fixes #9908: add type attribute to customizer compile button to prevent accidental submissions

customize.html

@@ -1717,7 +1717,7 @@ base_url: "../"
     </div>
     <p class="lead">Hooray! Your custom version of Bootstrap is now ready to be compiled. Just click the button below to finish the process.</p>
     <div class="bs-customize-download">
-      <button id="btn-compile" class="btn btn-block btn-lg btn-outline" onclick="_gaq.push(['_trackEvent', 'Customize', 'Download', 'Customize and Download']);">Compile and Download</button>
+      <button type="submit" id="btn-compile" class="btn btn-block btn-lg btn-outline" onclick="_gaq.push(['_trackEvent', 'Customize', 'Download', 'Customize and Download']);">Compile and Download</button>
     </div>
   </div><!-- /download -->
-</form>
\ No newline at end of file
+</form>