Bad parsing of `ps` output if command field is not the last one

Originally reported by Matthias Teege on google groups

Rex uses the ps command to gather the process information by splitting the output lines on whitespaces (/\s+/) to extract the different fields, while keeping the maximum number of extracted fields to the number of expected fields.

Since the command field of the output itself can contain spaces (e.g. /usr/bin/perl /usr/bin/perldoc Rex::Commands::Process), this method only can work if ps is asked to output the command field as the last one on the line (so it is prevented from being split on whitespaces as the maximum allowed number of splits already happened).

Rex either needs to somehow gather the process information in a machine-parsable format, or at least try to ensure that if command field is requested, then it is being used as last.

Start by locating the code that invokes ps and parses its process-information output, then inspect how requested fields are ordered and split. Done means commands containing spaces are parsed correctly when command is not last, using a machine-parsable format or ensuring that field is last.