Added getSelect to WebDriverElement

This PR includes the following changes -
1. `getSelect()` is ported from  CandyBean 1.1.3 to CandyBean 2.0.
2. A system test is added for `getSelect()`
3. Some system tests (doubleClick, dragNDrop, getAttribute, pauseUntilVisibleTest, isDisplay) are fixed and passing.
Please add the index parameter to the JavaDoc block.