version to 2.17.0
version to 2.17.0

This is a new major release.  This is needed b/c we drop support
for Ruby 1.8.7 with this release.

* mass-switch strings defs from `'` to `"` b6706b8
* cleanup "spaced out" array definitions 0601384
* update to our more modern conventions; drop support for ruby 1.8.7 aef302d
* only trap SIGINFO if available #292

redding/assert