Parameterized bpm limits

[aegershman]

part of #64

Continuation of #111 with specific focus on bpm limits, sysctl config set aside for separate PR

[aegershman]

after enabling bpm limits for processes and open files:

ulimit -n
1024

bpm pid yb-tserver
6955

tserver/1bf9fedf-147b-4353-b49e-02d57d065d3a:~# cat /proc/6955/limits 
Limit                     Soft Limit           Hard Limit           Units     
Max cpu time              unlimited            unlimited            seconds   
Max file size             unlimited            unlimited            bytes     
Max data size             unlimited            unlimited            bytes     
Max stack size            8388608              unlimited            bytes     
Max core file size        0                    unlimited            bytes     
Max resident set          unlimited            unlimited            bytes     
Max processes             30605                30605                processes 
Max open files            64000                64000                files     
Max locked memory         65536                65536                bytes     
Max address space         unlimited            unlimited            bytes     
Max file locks            unlimited            unlimited            locks     
Max pending signals       30605                30605                signals   
Max msgqueue size         819200               819200               bytes     
Max nice priority         0                    0                    
Max realtime priority     0                    0                    
Max realtime timeout      unlimited            unlimited            us   

notice how when running as root user (or performing su - vcap -c 'ulimit -n'), it still shows limits of 1024, but when querying the specific process under /proc/PROCPID/limits, it shows different (presumably correct) details

EDIT: okay so it's expected that these have different values for bpm from /proc/... vs. running ulimits as a user: https://serverfault.com/questions/788233/procs-limit-and-ulimit-f-dont-match