Reorganize tests, and switch to Jest about compose HOT 5 CLOSED

  compose
    ✓ should throw if middleware doesn not return a promise
    ✓ should keep the context across multiple middleware (1ms)
    ✓ should reject on errors in middleware (2ms)
    ✓ should not call next with middleware parameters
    ✓ should not call skipNext with middleware parameters (1ms)
    ✓ should throw if skipNext() is called multiple times at the beginning
    ✓ should throw if next() is called multiple times at the beginning (1ms)
    ✓ should throw if skipNext() is called multiple times at the end
    ✓ should throw if next() is called multiple times at the end
    ✓ should throw if skipNext() is called after next() (1ms)
    ✓ should throw if next() is called after skipNext()
    empty stack
      ✓ should propagate the return value of calling next (2ms)
      ✓ should catch an exception in next (1ms)
      ✓ should catch a rejected promise in next (1ms)
      ✓ should only accept functions for next
      ✓ should only accept functions for skipNext
    parameters
      ✓ should only accept an array of middleware
      ✓ should only accept middleware as functions (1ms)
    deep stack
      ✓ should call middleware stack in the right order (1ms)
      ✓ should be able to be called twice (1ms)
      ✓ should propagate the value of calling next
      with Skip at the end
        ✓ should propagate the value of calling skipNext
        ✓ should catch an exception in skipNext (1ms)
        ✓ should catch a rejected promise in skipNext