Add sounds and music

[antoinezanardi]

In order to improve the game's atmosphere, some sounds and background music must be added.

• For each role turn, add a sound which represents the role.
• If it's day time, first sheriff election or first angel vote, random background music (out of 3) must be played. Background music takes place in a village, with some crowd noises.
• If it's night time, random background music (out of 3) must be played. Background music takes place in a forest, with some various night noises.