add sounds effects for language change, wrong connection, and correct connection;
fix the bug that cannot go to the second level (need to initialize the total level at the beginning);
add the button of the levelviewcontroller in code, and segue to gameviewcontroller by level
program the segue structure instead of doing them in storyboard;
now the view controllers can pass language and level info between;
add chinese infos (spanish to be added);
implement short features, but will modify them after combining with sean's change;
add level3 to test short
modify game model based on sean's change
implement short features (the bulb will turn black the the circuit is short)
merge branch 'PowerUP_sound' into PowerUPBeta
Merge remote-tracking branch 'origin/PowerUPBeta' into PowerUPBeta
merge from PowerUP_sound manually