support Raspberry 3 B+ v1.2

[Sispheor]

It's seems that there is multiple version the last Rpi. The v1.2 use an armv6

import platform
print(platform.machine())

returns "armv6l".

It as been tested we can use the same snowboy compiled module.

Multiple solution to fix:

• create an alias armv6l that point to the existing armv7 folder
• copy armv7 folder to armv6l
• update the snowboy lib to point to armv7 when armv6l is detected here.

[LaMonF]

Done in #532 will be part of next release