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/compress-pdf.html

@@ -15,7 +15,7 @@
                     <div class="col-md-6">
                         <h2 th:text="#{compress.header}"></h2>
                         <form action="#" th:action="@{/compress-pdf}" method="post" enctype="multipart/form-data">
-					        <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multiple=false)}"></div>
+					        <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multiple=false, accept='application/pdf')}"></div>
 					        <div>
 					            <label for="optimizeLevel" th:text="#{compress.selectText.1}"></label>
 					            <select name="optimizeLevel" id="optimizeLevel">