Use ruby 2.x hash syntax

app/models/track.rb

@@ -6,7 +6,7 @@ class Track < ActiveRecord::Base
   validates_presence_of :name
 
   def file=(file)
-    sounds.build({:file => file})
+    sounds.build(file: file)
   end
 
   def sound

app/models/user.rb

@@ -9,11 +9,11 @@ class User < ActiveRecord::Base
   has_many :playlists
 
   validates :email,
-    :presence => true,
-    :uniqueness => true
+    presence: true,
+    uniqueness: true
   validates :password,
-    :presence => true,
-    :confirmation => true
+    presence: true,
+    confirmation: true
   validates_presence_of :password_hash
 
   def password=(plain_password)