Return result of $conditionResult after `wait` method call.

Needed for https://github.com/Behat/Mink/issues/301
Return result of $conditionResult after `wait` method call.
Tests added.

Needed for https://github.com/Behat/Mink/issues/301
Merge pull request #8 from aik099/driver-wait-return-value

Return result of $conditionResult after `wait` method call.