Add travis
Add Object#stub
Quell ruby warnings

We don't want ruby-warnings that we're overriding minitest's stub method
Assert that the stubbed method is intact during and after the block
Clearer variable-names
No need to safeguard block

If a block isn't given, a NameError is thrown
A stub can yield itself
Keep the number of arguments for the stubbed method
Object#stub can receive a block
Gather called methods with `Tunit::Mock`