Driver for Android is implemented. #64

Next steps:
- Implement driver for iOS
- Test refactor
- [Optional] add touch actions to drivers and elements
AndroidDriver & IOSDriver #64
#64. Some methods and interfaces were redesigned.

- Temporary IContextAware was added. It should be here till
https://github.com/SeleniumHQ/selenium/pull/301 is merged and new
Webdriver for .Net is published.
- Some methods were turned into properties.
- New tests for Android and IOS.
IContextAware is public
Tests were fixed
namespaces were improved
Merge pull request #70 from TikhomirovSergey/master

AndroidDriver & IOSDriver