If the setting to reconnect is unticked, and a user hits the e-stop button, and then ticks the box to reconnect, and then manually disconnects, the printer would automatically reconnect. This fixes that.
Also added an "unknown status" to the button, since the status should always be known, if it's not then it's not, you know? Yeah, me either.
Update icon to new FA icon to be compatible with octoprint 1.3.5's move to an update font awesome
Add a setting to allow changing of the command in situations where the user may wish to issue some other command other than M112
