Image stuff (#77)

Features
---------
Image to PDF supports multiple images, stretching and auto rotation
File inputs now only search for wanted file type
Settings now has a zip range so it can zip if you have more than x downloads (default 4)

extras
---------
DevTools support for easier development
Fix for temporary files for thread safety

src/main/resources/templates/home.html

@@ -40,7 +40,9 @@
 
             <!-- Features -->
             <div class="features-container container">
+                
                 <div th:replace="~{fragments/card :: card(cardTitle=#{home.merge.title}, cardText=#{home.merge.desc}, cardLink='merge-pdfs')}"></div>
+                
                 <div th:replace="~{fragments/card :: card(cardTitle=#{home.split.title}, cardText=#{home.split.desc}, cardLink='split-pdfs')}"></div>
                 <div th:replace="~{fragments/card :: card(cardTitle=#{home.rotate.title}, cardText=#{home.rotate.desc}, cardLink='rotate-pdf')}"></div>