Refactored contract.rb and contract_symbols.rb so everything is where it belongs.  Also enabled the dynamic 'add_contract' methods for operators.
Minor refactoring reducing the number of parameters to matching_instance_methods.
Updated split_method_name to properly identify operators ending in '=' instead of splitting out the final '=' as the suffix.
Added matrix.rb to so that we can exercise all the code that only runs when the contracts are included.  Fixed a few bugs that were found in doing so.  All paths are now relative to the 'src' directory.  In the future, this matrix.rb should probably be moved to a separate testing directory, since we don't need to give it our contracts in general, but it will be useful for validating our contracts against the original class.
Minor syntactic sugar - replaced a call to Array.push with the '<<' operator.
Merge pull request #4 from isupeene/refactor_contract_operator_symbols

Refactored contract.rb and contract_symbols.rb.