fixes #4889: btn-link disabled styles

docs/assets/css/bootstrap.css

@@ -3389,7 +3389,8 @@ input[type="submit"].btn.btn-mini {
 }
 
 .btn-link,
-.btn-link:active {
+.btn-link:active,
+.btn-link[disabled] {
   background-color: transparent;
   background-image: none;
   -webkit-box-shadow: none;
@@ -3412,6 +3413,11 @@ input[type="submit"].btn.btn-mini {
   background-color: transparent;
 }
 
+.btn-link[disabled]:hover {
+  color: #333333;
+  text-decoration: none;
+}
+
 .btn-group {
   position: relative;
   *margin-left: .3em;

less/buttons.less

@@ -208,7 +208,8 @@ input[type="submit"].btn {
 
 // Make a button look and behave like a link
 .btn-link,
-.btn-link:active {
+.btn-link:active,
+.btn-link[disabled] {
   background-color: transparent;
   background-image: none;
   .box-shadow(none);
@@ -224,3 +225,7 @@ input[type="submit"].btn {
   text-decoration: underline;
   background-color: transparent;
 }
+.btn-link[disabled]:hover {
+  color: @grayDark;
+  text-decoration: none;
+}