Overriding UiAutomator method clear with custom implementation using correctLongTap and longer time intervals

- Overriding clear with custom clear implementation
- Trying to select text with correctLongClick and waiting for more time 
- Falling back to UiAutomator method if element is not cleared.
- Added one more instruction for readme as i had to install all sdks and versions of android for building maven-android-sdk-deployer
- #1228
I think this should be [isEmpty](http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#isEmpty()) instead of equals("").