createSparkFlex inconsistency

[timtogan]

Right now the createSparkFlex(int, MotorConfig, SparkBaseConfig) method requires a MotorConfig, while the createSparkFlex(int) assumes that the MotorConfig is a Vortex one. We should prob either remove the MotorConfig parameter from createSparkFlex(int, MotorConfig, SparkBaseConfig) or add it to createSparkFlex(int) to make the methods consistent or maybe create both a method that requires a MotorConfig and does not for both methods.