Changed the order of procs in sys_proc

Just to match up better with how we define them in k_rtx.
Got ready for the set priority command proc

- changed num procs in k_rtx
- added barebones version of set priority command proc
- moved wall clock up in sys_proc
- changed k_process to initialize in the correct order
Implemented set priority command proc and fixed set_process_priority function

IN K_PROCESS:
- Now handle the case where we set priority of blocked processes
(whoops, should have fixed that in P2!)

IN SYS_PROC:
- Fully implemented the set priority command process :D
Now using RTX_ERR and better error message
Merge pull request #1 from edinkha/setpriorityproc

Merging the Setpriorityproc branch into Master.