Update Launchpad_Data_Processor.ino

Added SD write routine on Matt's behalf, but it is now within another boolean condition so that we can still test without the SD connected.

Also cut a bunch of code that was commented out and updated the start/stop/reset string indicators. Starts in idle mode by default, so if using serial monitor type !!! to begin transmission.
Merge pull request #10 from T52/Launchpad-Data-Processor---With-SD-Write-Options

Update Launchpad_Data_Processor.ino