Immediate pause and spacebar pause

Added immediate pause so grbl doesn’t wait until queued and cached
commands are completed before pausing.  Added spacebar pausing.
Merge branch 'fast_pause'
Allow running as a daemon

Added an init script and absolute path setting to config.js
Merge branch 'daemon'
Go to zero button

Added button to return to zero on G92 working coordinates.  Doesn’t
work after a reset.
Merge branch 'gotozero'
switch to grbl 0.9 baud