Made 'p4p' and 'p4proxy' completely synonomous.
Fixed an issue in mkdirs.sh where, if installing proxy with 'ServerType=p4p' in
the config file but not using '-t p4p', it would trying installing non-proxy
elements. Similar for p4broker. This was due to logic determining user intent
occuring only during command line processing needed to be deferred until after
the config file was processed, allowing either '-t p4p' on the command line or
'ServerType=p4p' in the mkdirs.cfg file to have the same effect, as intended.
command line processing