put version in its own file

(cherry picked from commit e053805f55b872e6926dfbfa14f38d1296e8b922)

lib/paperclip.rb

@@ -27,6 +27,7 @@
 
 require 'erb'
 require 'tempfile'
+require 'paperclip/version'
 require 'paperclip/upfile'
 require 'paperclip/iostream'
 require 'paperclip/geometry'
@@ -48,8 +49,6 @@
 # documentation for Paperclip::ClassMethods for more useful information.
 module Paperclip
 
-  VERSION = "2.3.2.beta2"
-
   class << self
     # Provides configurability to Paperclip. There are a number of options available, such as:
     # * whiny: Will raise an error if Paperclip cannot process thumbnails of 

lib/paperclip/version.rb

@@ -0,0 +1,5 @@
+module Paperclip
+
+  VERSION = "2.3.2.beta2" unless defined? Paperclip::VERSION
+
+end

paperclip.gemspec

@@ -1,5 +1,5 @@
 $LOAD_PATH << File.join(File.dirname(__FILE__), 'lib')
-require 'paperclip'
+require 'paperclip/version'
 
 include_files = ["README*", "LICENSE", "Rakefile", "init.rb", "{lib,tasks,test,rails,generators,shoulda_macros}/**/*"].map do |glob|
   Dir[glob]