[BUG] iOS silence mode doesn't play on .playUrl

[Stephane-Parent]

Describe the bug
When playing a sound from SoundPlayer.playUrl, no sound comes out if the Silence mode is ON (little switch on iPhone side).

To Reproduce
Steps to reproduce the behavior:

1. Boot your app
2. Play a sound with SoundPlayer.playUrl()
3. Hear the sound
4. Switch to silence mode
5. No more sound

Expected behavior
Expose a function to enable sound on silence mode. It would be more convenient to manage when to respect silence mode.

Platform (please complete the following information):

• OS: iOS
• lib version 0.13.2

Additional context
I bypass it by calling SoundPlayer.setSpeaker(false) before seeking. Seems like [session setActive:true error:nil]; is needed to bypass the Silence Mode. Once this function is called, Silence mode won't be respected anymore.

[Shenith]

Check this. #128