Correctly apply FAXOPT settings (V17, V27, V29) before starting spandsp layer

Correctly apply FAXOPT settings (V17, V27, V29) before starting spandsp layer

While the FAXOPT function could be used to set the modem capabilities, the
input to that function was not being applied correctly to the spandsp layer.
This patch applies the current model capabilities before starting the spandsp
layer.

(closes issue: ASTERISK-16409)
Reported by: Kristijan Vrban
Tested by: Matt Jordan, Matthew Nicholson
Patches:
  spandsp-modems-1.8.diff uploaded by mnicholson (license 5081)
  spandsp-modems-10.diff uploaded by mnicholson (license 5081)

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@352144 65c4cc65-6c06-0410-ace0-fbb531ad65f3