Add FilterChain#push as an alias to FilterChain#<<

lib/rackstash/filter_chain.rb

@@ -94,6 +94,7 @@ module Rackstash
       self
     end
     alias << append
+    alias push append
 
     # Filter the given event by calling each defined filter with it. Each filter
     # will be called with the current event and can manipulate it in any way.

spec/rackstash/filter_chain_spec.rb

@@ -152,6 +152,11 @@ describe Rackstash::FilterChain do
       expect(filter_chain << filter).to equal filter_chain
       expect(filter_chain[0]).to eql filter
     end
+
+    it 'can use #push alias' do
+      expect(filter_chain.push(filter)).to equal filter_chain
+      expect(filter_chain[0]).to eql filter
+    end
   end
 
   describe '#call' do