Write a general wrapper for Jpp command line tools

In order to create processing chains we could provide a class which wraps all the Jpp command line tools and allows to call them directly.

Let this example speak for itself:

# an example Python session...
from jppw import JppCMDWrapper

jppw = JppCMDWrapper()  # this will traverse the Jpp directory and parse the help output for each executable
output = jppw.JPrintHeader(inputFile='test.root')
do_something_useful_with(output)

output = jppw.JSirene(inputFile='another.root', detectorFile='orca.detx', numberOfHits=23)
...