Edited shotgun model, edited duck and shotgun fire sound effect

- Remodeled shotgun model so that the arm has a shirt on it. Looks a
lot better. Increased the aims size a little on the model as well.
- Edited shotgun sound effect so that it is not distorted and really
loud.
- Edited duck_2 call so it is amplified a little more.
- In game duck sound is louder then shotgun spray. This is a desired
feature so the user knows that they hit a duck, they can hear the audio
feedback better.