Support stateless component

[vincentbel]

Fix #14.

Here I remove react-hoist-generics-transform and do hoist in react-js-make-props-and-state-transform for the following reasons:

• It is just a little work to do the hoist in place(create type alias, insert it into SourceFile), no need to do lots of check in react-hoist-generics-transform.
• Stateless components also need to hoist, if we do hoist separately, we need to check again.

Besides, people seldom add a type alias if there are no props/state, So I inline it if it is empty:

// Before:
type MyComponentProps = {}
type MyComponentState = {}
class MyComponent extend React.Component<MyComponentProps, MyComponentState> {}


// After:
class MyComponent extend React.Component<{}, {}> {}

[theKashey]

Just a birthday present.