Logical updates and tweaks to defaults

This PR attempts to bring us more in-line with Punchblocks mainline changes that have been or are expected to be merged in. Better defaults and handling of parameters.
@runningferret I hope this isn't scope-creepy, but could you default speech_complete_timeout to -1?  This will improve the ability for this to get merged upstream, for the [reasons explained by Ben L](https://github.com/adhearsion/punchblock/pull/233#discussion_r19550952).  Thanks dude!