Fix for Rails 4 deprecation breaks Rails 5

[willc0de4food]

Reference: #3 , 3ee3fae
Rails 5 is complaining with the following:

! Unable to load application: ArgumentError: Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, to: :greeter).
/Users/tim/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.4/lib/active_support/core_ext/module/delegation.rb:155:in `delegate': Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, to: :greeter). (ArgumentError)
	from /Users/tim/.rvm/gems/ruby-2.4.0/gems/cached_counts-0.3.0/lib/cached_counts/active_record_base_methods.rb:19:in `singleton class'
	from /Users/tim/.rvm/gems/ruby-2.4.0/gems/cached_counts-0.3.0/lib/cached_counts/active_record_base_methods.rb:11:in `block in <module:ActiveRecordBaseMethods>'