Implemented a basic Volume Control
- Added a property which wraps the player.Volume
- Added a method to change the volume level
- Added a submenu to change the volume level

Added a method to clamp an input value between min/max

Minor Refactoring:
- Wrapped the IsMuted/IsIdle inside a property
- Remove the else level since it was redundant and this reduced nesting.
Changed the Menu items to use a lambda expression instead of a method to change the player.Volume
Fixes the behaviour that the player reverts to the default volume, if a stream is closed and reopened.
Merge branch 'feature/VolumeControl' into develop
Merge branch 'release/2014.08.25'
Merge pull request #1 from joshimoo/master

Implemented Volume Control