Use bundler.

Gemfile

@@ -0,0 +1,12 @@
+source "http://rubygems.org"
+
+gem 'eventmachine'
+gem 'json'
+gem 'mail'
+gem 'thin'
+gem 'sqlite3-ruby', :require => 'sqlite3'
+gem 'sinatra'
+gem 'sunshowers'
+
+# Required by activesupport, required by mail, but not listed.
+gem 'i18n'

bin/mailcatcher

@@ -1,5 +1,8 @@
 #!/usr/bin/env ruby
 
+require 'bundler'
+Bundler.setup
+
 $: << File.expand_path(File.join(File.dirname(__FILE__), '../lib'))
 
 require 'mail_catcher'

lib/mail_catcher.rb

@@ -1,4 +1,3 @@
-require 'rubygems'
 require 'eventmachine'
 require 'json'
 require 'ostruct'

mailcatcher.gemspec

@@ -16,6 +16,7 @@ Gem::Specification.new do |gem|
   gem.authors = ["Samuel Cochran"]
   gem.email = "sj26@sj26.com"
   
+  gem.add_dependency 'bundler'
   gem.add_dependency 'eventmachine'
   gem.add_dependency 'json'
   gem.add_dependency 'mail'