(optionally) change process name of children

settings the process title to a human readable name helps
to identify which subprocess is doing what. besides looking nice
it also helps to give a better inside in what parts of bucky are
using resources when looking at the output of ps, top and alikes.
remove log.debug statemens from udpserver when not running in debug mode and use arguments for string formatting on log functions

the log.debug statements are taking up a significant part of execution time (as measured by cProfile) this patch makes it so that these statement are only loaded when debug mode is True.

Changing all places (where possible) which call logger functions in combination with string formatting to use arguments on the logger function instead of doing the string formatting in place. This is a (micro-)optimalisation when the message will not be logged