Cleanup printed output. Showtask list

 This change includes the following:
  * Display task list executing
  * Combine redundant messages
  * Check system requirements up front
  * Show error from main ant package build process on error
  * Check for existence of 'template' directory before accessing
  * Capture KeyboardInterrupt exception to gracefully exit on Ctl+C
It prevents a newline so that at the end of the function the "ok" is on the same line.
  "Checking system requirements...ok"
vs. 
  "Checking system requirements...
  ok"
An  alternate way to do this would be the Python 3.x way which we could do with:
  from __future__ import print_function
  print('.',end="",flush=True)