Add Crystal support

Author: veelenga

src/main/scala/com/codacy/plugins/api/languages/Language.scala

@@ -76,6 +76,7 @@ object Languages {
                                PHP,
                                Python,
                                Ruby,
+                               Crystal,
                                Java,
                                CoffeeScript,
                                Swift,
@@ -252,6 +253,8 @@ object Languages {
 
   case object Groovy extends Language(extensions = Set(".groovy"))
 
+  case object Crystal extends Language(extensions = Set(".cr"))
+
   // Others
 
   case object Perl extends Language(extensions = Set(".pl"))