Make mailcatcher aware of its version.

lib/mail_catcher.rb

@@ -55,6 +55,7 @@ module_function
     @@defaults.dup.tap do |options|
       OptionParser.new do |parser|
         parser.banner = "Usage: mailcatcher [options]"
+        parser.version = File.read(File.expand_path("../../VERSION", __FILE__))
 
         parser.on("--ip IP", "Set the ip address of both servers") do |ip|
           options[:smtp_ip] = options[:http_ip] = ip

mailcatcher.gemspec

@@ -15,7 +15,7 @@ Gem::Specification.new do |s|
   s.homepage = "http://mailcatcher.me"
 
   s.files = Dir[
-    "README.md", "LICENSE",
+    "README.md", "LICENSE", "VERSION",
     "bin/*",
     "lib/**/*.rb",
     "public/images/**/*",