drive Progress Bar from fifo file

[alpartis]

1. Add a progress bar to Booty.qml between the text in the middle and the launcher button

2. C++ function in thread in main.cpp must create/open/read from FIFO file descriptor in the local filesystem (named "fifo_pipe")

   • expecting to read "Step 1 of 8" for example
   • C++ function should call QML Javascript function to update the progress bar accordingly

3. In a separate Bash shell/console, the user should be able to write strings to the FIFO like so:

   $ echo "Step 2 of 8" > ./fifo_pipe