Only check binary dependency when audio is played

[user202729]

In the current implementation, the audio is only loaded after play or output is called, so the check is done before the program make any HTTP request.

I don't have sox installed, but I have another audio player, and I want to use that, so it should not error out.

[coveralls]

Coverage increased (+0.09%) to 76.406% when pulling ac518ad on user202729:lazycheckbin into fbcd022 on desbma:master.

[desbma]

I have removed the bin_dep check completely instead.

Users that are trying to play sound without SoX installed will get an error anyway.

And users that only want to download the sound don't need the check.