Hygiene: Remove unnecessary Less vars

Removing unnecessary Less vars, which are not in use any more.
Also slightly modifying code comment for better code style.

Change-Id: I6e2417561afb03225eaca99ea93135f975a51593

resources/skins.minerva.base.styles/common.less

@@ -2,9 +2,6 @@
 @import 'minerva.variables.less';
 @import 'minerva.mixins.less';
 
-@imageReplacementColor: #706e6e;
-@inputsBoxBorderColor: #e1e1e1;
-
 // Reusable components
 //
 // Styleguide 6.
@@ -17,8 +14,8 @@
 // under a different circumstance
 //
 // Markup:
-// <div style="width:50px;height:50px;border: solid 1px red">
-// <input type="file" class="cloaked-element">
+// <div style="width:50px; height:50px; border:1px solid red;">
+//   <input type="file" class="cloaked-element">
 // </div>
 //
 // Styleguide 6.1.

resources/skins.minerva.base.styles/pageactions.less

@@ -1,8 +1,6 @@
 @import 'minerva.variables';
 @import 'minerva.mixins';
 
-@borderBottomColor: #cacaca;
-
 // hide menu items when not possible to use
 .client-nojs #ca-watch,
 #ca-talk.selected {