Address issue#61 by allowing only recognized file types to be picked for upload

src/web/templates/index.html

@@ -167,13 +167,13 @@
 
     <hr/>
     <h2>Upload File</h2>
-    <p>Uploads file to <tt>{{base_dir}}</tt>. Max file size is set to {{max_file_size / 1024 /1024 }}MB</p>
+    <p>Uploads file to <tt>{{base_dir}}</tt>. The largest file size accepted is {{max_file_size / 1024 /1024}} MB</p>
     <table style="border: none">
         <tr style="border: none">
             <td style="border: none; vertical-align:top;">
 		<form action="/files/upload" method="post" enctype="multipart/form-data">
                     <label for="file">File:</label>
-                    <input type="file" name="file" />
+                    <input type="file" name="file" accept="{{valid_file_suffix}}" />
                     <input type="submit" value="Upload" />
                 </form>
             </td>

src/web/web.py

@@ -73,7 +73,7 @@ def index():
         running_env=running_env(),
         server_info=server_info,
         netinfo=get_network_info(),
-        valid_file_suffix=", ".join(VALID_FILE_SUFFIX),
+        valid_file_suffix="."+", .".join(VALID_FILE_SUFFIX),
         removable_device_types=REMOVABLE_DEVICE_TYPES,
         harddrive_file_suffix=HARDDRIVE_FILE_SUFFIX,
         cdrom_file_suffix=CDROM_FILE_SUFFIX,