Audio recording for macOS

[Nephyx]

Added audio recording and playback for macOS using Apple's Objective-C API via pyobjus.
Audio files are recorded with 44.1 kHz sample rate in WAV format.

Closes issue #282.

[tito]

You should not pass a default value that point on nothing :) Should be None by default.

[Nephyx]

Tried without passing a value of None, but I started getting the following error:
`>>> from plyer import audio

audio.start()
Traceback (most recent call last):
File "/Users/maroskovac/Dev/plyer/plyer/utils.py", line 96, in _ensure_obj
obj = mod.instance()
File "/Users/maroskovac/Dev/plyer/plyer/platforms/macosx/audio.py", line 82, in instance
return OSXAudio()
TypeError: init() takes exactly 2 arguments (1 given)
Traceback (most recent call last):
File "", line 1, in
File "/Users/maroskovac/Dev/plyer/plyer/facades/audio.py", line 65, in start
self._start()
File "/Users/maroskovac/Dev/plyer/plyer/facades/audio.py", line 98, in _start
raise NotImplementedError()
NotImplementedError`

[tito]

It would be better to catch the error and raise an exception if something failed, rather than completely ignore.

[Nephyx]

@tito here's a quick summary of my commits addressing your changes request:

• removed all prints
• kept passing file_path with default value of None, as removing it as per your suggestion causes NotImplementedError (more in my reply to your change request)
• added raising exceptions in case of recorder or player initialization errors (using only one NSError instance because of segmentation faults in case of multiple NSError allocs and actually, there's no need to have more than one instance)

[tito]

Thanks you!