added voicemail length configuration
improved voicemail length config
feature: #1) implemented TTS with language swithcing capabilities.
#2) implemented defining DTMF length (new Media property:
ANSWER_INPUT_LENGTH)
feature: added no answer timeout for open and closed questions
fix: issue with setting timeout for open and closed questions
fix: issue with international number SMS
feature: added mediaproperties for DTMFTerm, Beep. Control speed of TTS
fix: disconnect the call when questionType is null
change log update
merge pre_release_0.7.0 into develop