[core] remove useless static methods

Signed-off-by: Pierre Mazière <pierre.maziere@gmx.com>

lib/Format.php

@@ -118,7 +118,7 @@ class Format{
     }
 
     static public function create($nameFormat){
-        if( !static::isValidNameFormat($nameFormat) ){
+        if( !preg_match('@^[A-Z][a-zA-Z]*$@', $nameFormat)){
             throw new \InvalidArgumentException('Name format must be at least one uppercase follow or not by alphabetic characters.');
         }
 
@@ -155,10 +155,6 @@ class Format{
         return $dirFormat;
     }
 
-    static public function isValidNameFormat($nameFormat){
-        return preg_match('@^[A-Z][a-zA-Z]*$@', $nameFormat);
-    }
-
     /**
     * Read format dir and catch informations about each format depending annotation
     * @return array Informations about each format