Added tests for executeScript
Added tests for executeScript

Closes #457

jordi12100/Mink,minkphp/Mink,talib570/Mink,jhedstrom/Mink,Behat/Mink,minkphp/Mink,Chekote/Mink,handrus/Mink,stof/Mink,aik099/Mink,jhedstrom/Mink,jordi12100/Mink,Chekote/Mink,talib570/Mink