Update the initial UI open to use Launchy

This should make it work across platform, when previously it would
only work in OSX.

gitdocs.gemspec

@@ -34,6 +34,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'shell_tools', "~> 0.1.0"
   s.add_dependency 'mimetype-fu', "~> 0.1.2"
   s.add_dependency 'eventmachine', '>= 1.0.3'
+  s.add_dependency 'launchy', '~> 2.4.2'
 
   s.add_development_dependency 'minitest', "~> 5.0.8"
   s.add_development_dependency 'rake'

lib/gitdocs/server.rb

@@ -4,6 +4,7 @@
 require 'uri'
 require 'haml'
 require 'mimetype_fu'
+require 'launchy'
 
 module Gitdocs
   class Server
@@ -152,7 +153,7 @@ def wait_for_start_and_open(restarting)
           TCPSocket.open('127.0.0.1', @port).close
           @manager.log('Web server running!')
           if !restarting && @manager.config.global.load_browser_on_startup
-            system("open http://localhost:#{@port}/")
+            Launchy.open("http://localhost:#{@port}/")
           end
         rescue Errno::ECONNREFUSED
           sleep 0.2