pyInterface: change config __init__ to initialize method

change __init__ method of config class to an initialize method, so we can
return True/False to indicate whether initialization succeeded or failed. Hence
we can have proper exception handling and don't have to use sys.exit(1) if
exceptions do happen. Change files affected by this update accordingly. Also
implement some checks to see if the key/amplitude directory is a valid
directory.
not ready: calcAmplitudes