support for absolute path and file:// paths

Add playableDuration property to onProgress event

Use markdown syntax to display images inline

Documentation updates

In order to use this native component the video resources must be
added to the project and bundled on build.

- Also remove a duplicate data property
- Fix linkrot in README and add Examples section

Update react-native requirement in example

react-native-video wants ^0.4.0, so let's give it to it.

This to avoid to send an errors stack caused by the `NaN` given in the JSON of the RCTEventDispatcher.

fixes #26