fix : import-picture-panel

- When imported 1 picture and then importing another one, the picture
  preview was not cleaned and was displaying the two images side by side.
  Fixed in ImportController.js
- Switched all double-quoted strings in ImportController to single-quoted
  strings. Should enforce this using jshint
- Aligned all inputs in the import picture panel
- Renamed 'Preview :' import section to 'Info :'. Mostly it's to make it
  shorter, but also I'd like to display additional information to the
  right of the preview in the future.

templates/settings/import.html

@@ -5,7 +5,7 @@
   <div class="settings-item">
     <form action="" method="POST" name="import-form">
       <div class="import-section">
-        <span class="import-section-title">File :</span>
+        <span class="import-section-title  import-section-title-small">File :</span>
         <button type="button" class="button  button-primary file-input-button">Browse</button>
         <span class="file-input-status"></span>
         <input style="display:none"
@@ -13,11 +13,11 @@
           value="file" accept="image/*"/>
       </div>
       <div class="import-section import-section-disabled">
-        <span class="import-section-title" style="vertical-align:top">Preview :</span>
+        <span class="import-section-title  import-section-title-small" style="vertical-align:top">Info :</span>
         <div class="import-section-preview"></div>
       </div>
       <div class="import-section import-section-disabled">
-        <span class="import-section-title">Size :</span>
+        <span class="import-section-title  import-section-title-small">Size :</span>
         <input type="text" disabled="disabled" class="textfield import-resize-field" name="resize-width"/>x
         <input type="text" disabled="disabled" class="textfield import-resize-field" name="resize-height"/>
       </div>