All abbreviations are not upper case initialisms

Read more:
 * http://developers.whatwg.org/text-level-semantics.html#the-abbr-element
 * http://en.wikipedia.org/wiki/Abbreviation
 * http://en.wikipedia.org/wiki/Initialism

docs/assets/css/bootstrap.css

@@ -416,8 +416,6 @@ em {
   color: #999999;
 }
 abbr {
-  font-size: 90%;
-  text-transform: uppercase;
   border-bottom: 1px dotted #ddd;
   cursor: help;
 }

less/type.less

@@ -155,8 +155,6 @@ em {
 
 // Abbreviations and acronyms
 abbr {
-  font-size: 90%;
-  text-transform: uppercase;
   border-bottom: 1px dotted #ddd;
   cursor: help;
 }