Enable snowboy to use several wakeword models

[dalgwen]

Snowboy could use several wakeword models, not only the first one.

Description

Fix #2498

How to test

Use snowboy, with several hotword model at the same time.
Every one of them should wake mycroft.

Contributor license agreement signed?

CLA [ ]
Not yet, I'm in processing. But I think that for a change this small, it will not be a problem ;-)

[devs-mycroft]

Hello, @dalgwen, thank you for helping with the Mycroft project! We welcome everyone
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for Everyone.

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Please visit https://mycroft.ai/cla to initiate this one-time signing. Thank
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[dalgwen]

I forgot to mention snowboy code documentation to back this modification :

// " In the case that more than one hotword exist in the
// provided models, RunDetection() will return the index of the hotword, if
// the corresponding hotword is triggered."

[forslund]

Thanks @dalgwen looks nice and simple. Will merge once the CLA is received. (We're require it for all contributions no matter how small so we are consistent)

[dalgwen]

It's OK, I just signed the CLA. 👍

[krisgesling]

Thanks @dalgwen.

Received the CLA. Merging now.