tests passing in 1.9.3, 2.0.0 and still passing in 2.1.0

Ran into trouble using repositories on 2.0.0.  Confirmed same on 1.9.3 and noted it was working on 2.1.0.

You will see that the fix is very straight forward and I have a feeling it is a bug in 2.1.0 that is allowing the use of include within a class level of execution.

Tried to track down some evidence of the 2.1.0 bug theory, best i could find that explains the expected behaviours:  http://stackoverflow.com/a/7296037

Original Exception:

```
% rake test
/Users/davetheninja/Work/oss/chassis-ah/lib/chassis/strategy.rb:83:in `included': private method `include' called for Chassis::Repo:Class (NoMethodError)
	from /Users/davetheninja/Work/oss/chassis-ah/lib/chassis/repo.rb:27:in `include'
	from /Users/davetheninja/Work/oss/chassis-ah/lib/chassis/repo.rb:27:in `<class:Repo>'
	from /Users/davetheninja/Work/oss/chassis-ah/lib/chassis/repo.rb:20:in `<module:Chassis>'
	from /Users/davetheninja/Work/oss/chassis-ah/lib/chassis/repo.rb:3:in `<top (required)>'
	from /Users/davetheninja/Work/oss/chassis-ah/lib/chassis.rb:63:in `require_relative'
	from /Users/davetheninja/Work/oss/chassis-ah/lib/chassis.rb:63:in `<top (required)>'
	from /Users/davetheninja/Work/oss/chassis-ah/test/test_helper.rb:4:in `require'
	from /Users/davetheninja/Work/oss/chassis-ah/test/test_helper.rb:4:in `<top (required)>'
	from /Users/davetheninja/Work/oss/chassis-ah/test/chassis_test.rb:1:in `require_relative'
	from /Users/davetheninja/Work/oss/chassis-ah/test/chassis_test.rb:1:in `<top (required)>'
	from /Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
	from /Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
	from /Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/gems/rake-10.1.1/lib/rake/rake_test_loader.rb:10:in `block (2 levels) in <main>'
	from /Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/gems/rake-10.1.1/lib/rake/rake_test_loader.rb:9:in `each'
	from /Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/gems/rake-10.1.1/lib/rake/rake_test_loader.rb:9:in `block in <main>'
	from /Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/gems/rake-10.1.1/lib/rake/rake_test_loader.rb:4:in `select'
	from /Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/gems/rake-10.1.1/lib/rake/rake_test_loader.rb:4:in `<main>'
rake aborted!
Command failed with status (1): [ruby -I"lib" -I"/Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/gems/rake-10.1.1/lib" "/Users/davetheninja/.rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/gems/rake-10.1.1/lib/rake/rake_test_loader.rb" "test/**/*_test.rb" ]

Tasks: TOP => test
(See full trace by running task with --trace)
```