do not auto-require torqbox server and put it in a logical group

rack/Gemfile-jruby

@@ -3,7 +3,9 @@ source 'http://rubygems.org'
 gem 'rack', '1.5.2'
 gem 'json', '1.7.6'
 
-gem 'torqbox', '0.1.7'
-
 gem "rubyzip", "~> 1.0.0"
 gem "zip-zip", "~> 0.1"
+
+group :server do
+  gem 'torqbox', '0.1.7', :require => false
+end