simplify code for input-prepend/append in inline and search forms

docs/assets/css/bootstrap.css

@@ -982,6 +982,7 @@ select:focus:required:invalid:focus {
 }
 .input-prepend,
 .input-append {
+  display: inline-block;
   margin-bottom: 5px;
 }
 .input-prepend input,
@@ -1087,11 +1088,11 @@ select:focus:required:invalid:focus {
 .form-inline .input-prepend {
   display: inline-block;
 }
-.form-search .input-append .add-on,
-.form-search .input-prepend .add-on,
-.form-inline .input-append .add-on,
-.form-inline .input-prepend .add-on {
-  vertical-align: middle;
+.form-search .input-append,
+.form-inline .input-append,
+.form-search .input-prepend,
+.form-inline .input-prepend {
+  margin-bottom: 0;
 }
 .form-search .radio,
 .form-search .checkbox,

less/forms.less

@@ -361,6 +361,7 @@ select:focus:required:invalid {
 // Allow us to put symbols and text within the input field for a cleaner look
 .input-prepend,
 .input-append {
+  display: inline-block;
   margin-bottom: 5px;
   input,
   select,
@@ -456,12 +457,12 @@ select:focus:required:invalid {
 .form-inline .input-prepend {
   display: inline-block;
 }
-// Make the prepend and append add-on vertical-align: middle;
-.form-search .input-append .add-on,
-.form-search .input-prepend .add-on,
-.form-inline .input-append .add-on,
-.form-inline .input-prepend .add-on {
-  vertical-align: middle;
+// Remove margin for input-prepend/-append
+.form-search .input-append,
+.form-inline .input-append,
+.form-search .input-prepend,
+.form-inline .input-prepend {
+  margin-bottom: 0;
 }
 // Inline checkbox/radio labels (remove padding on left)
 .form-search .radio,