small ui fixes in Studio - textbooks upload and loading font-size

cms/static/sass/elements/_forms.scss

@@ -59,6 +59,10 @@ textarea.text {
 // forms - additional UI
 form {
 
+  input[type=file] {
+    line-height: 1;
+  }
+
   .note {
     @include box-sizing(border-box);
 

common/static/sass/_mixins.scss

@@ -268,6 +268,7 @@
 .ui-loading {
   @include animation(fadeIn $tmg-f2 linear 1);
   @extend %ui-well;
+  @extend %t-base-copy;
   opacity: .6;
   background-color: $white;
   padding: ($baseline*1.5) $baseline;