Minor updates

So nothing groundbreaking in this release, just firming things up and
pushing out changes because they have sat in the repo long enough.

• bump up to ring 0.1.7
• optionaly serve static cljsjs resources see https://figwheel.org/config-options#cljsjs-resources
• experimental - support for a cross over :nodejs Extra Main target to compile a project for the browser and node -- this more than likely wont work in many cases
• change the way that figwheel.main detects whether clj is launching figwheel from a project directory
• CSS reloading improvement
• ensure not zero exit when not watching or building once
• make syntax errors log at level :warn