Add a function to read the btime (boot time) from /proc/stat, also move reading of /proc/stat for ticks used to a function
Add starttime and runtime to the process detail display and fix cpu percent calculation..

Fix cpu percent calculation which was broken by previous commit (calculated using ticks_passed which is unused since being moved to the parametres struct). Now removed the ticks_passed altogether.
Add first line to output containing invocation name, time, uptime and load averages