run without root permission

[harp-intel]

This is an experimental PR that allows running perf-collect as a regular, non-root, user.

The caveat is that a 'root' user must pre-configure the system before running perf-collect. There are three configuration items:

• sysctl -w kernel.perf_event_paranoid=0
• sysctl -w kernel.nmi_watchdog=0
• write '125' to all perf_event_mux_interval_ms files found under /sys/devices/*. for i in $(find /sys/devices -name perf_event_mux_interval_ms); do echo 125 > $i done