tests pass using bundler, once yaml and multi_json are properly required

[kornypoet]

When running tests using bundle exec rake rspec, the require statement for yaml is missing and causing tests to fail.

The require statement for this library is contained within the ConfigFile#read_yaml method; similarly the require statement for multi_json is contained in ConfigFile#read_json. Since both methods are top-level features, and are fully tested, these require statements should be moved into the main class loader. This will cause no dependency issues as yaml has been a standard ruby library since 1.8.7 and multi_json is listed as a dependency in both the Gemfile and the gemspec.

Break the silence, yo.