Merge pull request #149 from BnLG/autoprov

Snom, Yealink, allow autoprov with SIP TLS

Hello,
When a device is connected to the stack, for the first time, an autoprov configuration template is generated.
There's no problem if this template uses SIP TLS, device will properly reach the stack when provisioning using the  Provision Extension method.
However, SRTP can't be used here, because autoprov stack SIP template has it disabled (for good reasons *).
Let's then disable SRTP when in autoprov mode, for both SIP TLS validated plugin ; Snom & Yealink.
Thx 👍
BTW, while here, would really be nice for the autoprov mode to inherit from the global SIP template, so that it would really help for example in NATed environment etc... (see Wazo ticket #5571 / #6066).
(*) Note that even if autoprov mode would inherit from the global SIP template, we would not be able to enable SRTP there (media_encryption = sdes), because then it would break provisioning using the  Provision Extension method for devices not supporting SRTP.

Reviewed-by: Alexandre Fournier <None>