fixing wrong constants

app/models/collections/public_context.rb

 ##
 # This class represents an specification for listing collections
 # The PublicContext class specify all collections with field privacy=public
-class Collections::PublicContext < Collections::Context
+class Collections::PublicContext < Context
 
   def from
     'Collection'

app/models/collections/user_context.rb

-class UserContext < Collections::Context
+class UserContext < Context
 
   def initialize(user)
     @user = user

app/models/collections/user_private_context.rb

 ##
 # This class represents an specification for listing collections
 # The PublicContext class specify all collections with field privacy=public
-class Collections::UserPrivateContext < Collections::UserContext
+class Collections::UserPrivateContext < UserContext
 
   def privacy
     'private'

app/models/collections/user_public_context.rb

 ##
 # This class represents an specification for listing collections
 # The PublicContext class specify all collections with field privacy=public
-class Collections::UserPublicContext < Collections::UserContext
+class Collections::UserPublicContext < UserContext
 
   def privacy
     'public'