Remove null byte from proctitle

[look]

Null bytes cause problems with NewRelic RPM:

ERROR : Failed to harvest profile_data data, resetting. Error: ERROR : ArgumentError: string contains null byte

This happens because File.basename raises an exception when the string contains a null byte.

According to @ageweke in 32791ce1531a8cf9f533254204694915394fecba using a null byte is no longer necessary. I have not found any examples online that use the null byte.