avoid ActiveRecord 5.0 deprecations

Author: jrochkind

lib/oai/provider/model/activerecord_caching_wrapper.rb

@@ -111,7 +111,7 @@ def select_partial(token)
     end
 
     def sweep_cache
-      OaiToken.destroy_all(["created_at < ?", Time.now - expire])
+      OaiToken.where(["created_at < ?", Time.now - expire]).destroy_all
     end
 
     def hydrate_records(records)

test/activerecord_provider/database/0001_oaipmh_tables.rb

@@ -1,4 +1,4 @@
-class OaipmhTables < ActiveRecord::Migration
+class OaipmhTables < ActiveRecord::Migration[4.2]
   def self.up
     create_table :oai_tokens do |t|
       t.column :token,      :string,  :null => false

test/activerecord_provider/models/exclusive_set_dc_field.rb

@@ -3,7 +3,7 @@ class ExclusiveSetDCField < ActiveRecord::Base
 
   def self.sets
     klass = Struct.new(:name, :spec)
-    self.uniq.pluck('`set`').compact.map do |spec|
+    self.distinct.pluck('`set`').compact.map do |spec|
       klass.new("Set #{spec}", spec)
     end
   end