perf(api): Refactored API.

You no longer need to use the prepInjection() function to create Injectable and Injector instances.
Instead we provide you wiht the Injectable and Injector directly and will manage the wiring up for
you.  Please read docs for updated usage.

BREAKING CHANGE: prepInjection() dropped and Injector api updated.

README.md

@@ -8,6 +8,8 @@
 [![MIT License](https://img.shields.io/npm/l/react-injectables.svg?style=flat-square)](http://opensource.org/licenses/MIT)
 [![Codecov](https://img.shields.io/codecov/c/github/ctrlplusb/react-injectables.svg?style=flat-square)](https://codecov.io/github/ctrlplusb/react-injectables)
 
+Tiny, and the only dependency is a peer dependency of React.
+
 ## What is this for?
 
 Envision you have the following component tree: