Immediately pause machine/spacebar pause

Added immediate pausing of machine using grbl ! and ~.  This skips ahead of the current queue and any commands cached on the grbl controller.
Daemon mode/absolute path

Added init script and changes to run the server as a daemon on system startup.  You need to specify an absolute path in config.js.  To use the init script modify it based on your system settings (see init script comments), copy it to /etc/init.d/grblweb, and run "update-rc.d grblweb defaults."
Go to zero button

Added a button that returns to 0,0,0 on working coordinates.  USE WITH CAUTION!  After a reset this will go somewhere else entirely.
Immediate pause and spacebar pause

Use grbl commands ! and ~ to pause and unpause, jumping ahead of the GRBLWeb queue and any commands cached on the grbl controller.  This immediately pauses the machine.  Also added spacebar pause.
Merge branch 'daemon' into grblweb-mod
Merge branch 'gotozero' into grblweb-mod