#2 OS checks should be more resilient

[Chris Gilbert]

Currently OS checks are subject to issues when versions of the command line tools differ to those they were tested on. To improve this situation we need to:

a) Find APIs in each operating system to query directly, for disk checks, CPU and memory
b) Make sure these methods are resilient and won't break easily in the future
c) Test on other languages, to ensure NPA works with different regional settings than English