hopefully this works

Author: jameshfisher

lib/pusher.rb

@@ -60,6 +60,7 @@ def default_client
   end
 end
 
+require 'pusher/version'
 require 'pusher/channel'
 require 'pusher/request'
 require 'pusher/resource'

lib/pusher/request.rb

@@ -9,7 +9,7 @@ class Request
     def initialize(client, verb, uri, params, body = nil)
       @client, @verb, @uri = client, verb, uri
       @head = {
-        'X-Pusher-Library' => 'pusher-http-ruby ' + "1.2.0.rc2" # TODO deduplicate
+        'X-Pusher-Library' => 'pusher-http-ruby ' + Pusher::VERSION
       }
 
       @body = body

lib/pusher/version.rb

@@ -0,0 +1,3 @@
+module Pusher
+  VERSION = '1.2.0.rc2'
+end

pusher.gemspec

@@ -1,7 +1,10 @@
 # -*- encoding: utf-8 -*-
+
+require_relative 'lib/pusher/version'
+
 Gem::Specification.new do |s|
   s.name        = "pusher"
-  s.version     = "1.2.0.rc2"
+  s.version     = Pusher::VERSION
   s.platform    = Gem::Platform::RUBY
   s.authors     = ["Pusher"]
   s.email       = ["support@pusher.com"]