fix parse error in .kitchen.yml

```
$ bundle exec kitchen test default-centos-64
-----> Starting Kitchen (v1.0.0.beta.4)
>>>>>> ------Exception-------
>>>>>> Class: Kitchen::UserError
>>>>>> Message: Error parsing /home/glen/vagrant/sysctl/.kitchen.yml
>>>>>> ----------------------
>>>>>> Please see .kitchen/logs/kitchen.log for more details

$ cat .kitchen/logs/kitchen.log
I, [2013-11-07T14:14:07.883957 #5552]  INFO -- Kitchen: -----> Starting Kitchen (v1.0.0.beta.4)
E, [2013-11-07T14:14:07.888185 #5552] ERROR -- Kitchen: ------Exception-------
E, [2013-11-07T14:14:07.888239 #5552] ERROR -- Kitchen: Class: Kitchen::UserError
E, [2013-11-07T14:14:07.888277 #5552] ERROR -- Kitchen: Message: Error parsing /home/glen/vagrant/sysctl/.kitchen.yml
E, [2013-11-07T14:14:07.888312 #5552] ERROR -- Kitchen: ---Nested Exception---
E, [2013-11-07T14:14:07.888347 #5552] ERROR -- Kitchen: Class: Psych::SyntaxError
E, [2013-11-07T14:14:07.888381 #5552] ERROR -- Kitchen: Message: (<unknown>): mapping values are not allowed in this context at line 20 column 8
E, [2013-11-07T14:14:07.888416 #5552] ERROR -- Kitchen: ------Backtrace-------
E, [2013-11-07T14:14:07.888451 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/loader/yaml.rb:114:in `rescue in parse_yaml_string'
E, [2013-11-07T14:14:07.888485 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/loader/yaml.rb:110:in `parse_yaml_string'
E, [2013-11-07T14:14:07.888520 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/loader/yaml.rb:80:in `yaml'
E, [2013-11-07T14:14:07.888556 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/loader/yaml.rb:72:in `combined_hash'
E, [2013-11-07T14:14:07.888590 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/loader/yaml.rb:62:in `read'
E, [2013-11-07T14:14:07.888624 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/config.rb:174:in `data'
E, [2013-11-07T14:14:07.888658 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/config.rb:66:in `suites'
E, [2013-11-07T14:14:07.888693 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/config.rb:101:in `build_instances'
E, [2013-11-07T14:14:07.888728 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/config.rb:72:in `instances'
E, [2013-11-07T14:14:07.888761 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/cli.rb:308:in `get_filtered_instances'
E, [2013-11-07T14:14:07.888800 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/cli.rb:294:in `parse_subcommand'
E, [2013-11-07T14:14:07.888834 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/cli.rb:108:in `block in test'
E, [2013-11-07T14:14:07.888868 #5552] ERROR -- Kitchen: /usr/share/ruby/1.9/benchmark.rb:280:in `measure'
E, [2013-11-07T14:14:07.888901 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/cli.rb:104:in `test'
E, [2013-11-07T14:14:07.888936 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/thor-0.18.1/lib/thor/command.rb:27:in `run'
E, [2013-11-07T14:14:07.888970 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/thor-0.18.1/lib/thor/invocation.rb:120:in `invoke_command'
E, [2013-11-07T14:14:07.889005 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/cli.rb:255:in `invoke_task'
E, [2013-11-07T14:14:07.889040 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/thor-0.18.1/lib/thor.rb:363:in `dispatch'
E, [2013-11-07T14:14:07.889074 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/thor-0.18.1/lib/thor/base.rb:439:in `start'
E, [2013-11-07T14:14:07.889109 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/bin/kitchen:13:in `block in <top (required)>'
E, [2013-11-07T14:14:07.889145 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/lib/kitchen/errors.rb:81:in `with_friendly_errors'
E, [2013-11-07T14:14:07.889189 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/gems/test-kitchen-1.0.0.beta.4/bin/kitchen:13:in `<top (required)>'
E, [2013-11-07T14:14:07.889225 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/bin/kitchen:23:in `load'
E, [2013-11-07T14:14:07.889259 #5552] ERROR -- Kitchen: /home/glen/vagrant/sysctl/ruby/1.9/bin/kitchen:23:in `<main>'
E, [2013-11-07T14:14:07.889294 #5552] ERROR -- Kitchen: ----------------------

```