Implemented cpu()
 * cat /proc/stat twice with 1 second wait
 * usage is total - idle (jiffies)
 * output currently seems suspiciously low
add disk and network stubs
api: add filesystem and remove uptime
main(): don't process connect() output if return code was nonzero
add reference.txt with details of vmstat output (from man page)
increase default timeout from 10 to 30 seconds
implement different units for each info type
implement disk() for disk io in MB/s
memory: improve memory performance data to follo rrd spec
fix: make output a sentence
cpu: fix irq and softirq
implement general method for printing detail output and apply it to load()
refactor detail for memory and cpu
fix: percentages were not being displayed properly, round level to 2 sig fig in output
Implement filesystem():
 * add extra variable to finish() so we can specify which filesystem
 * choose / as default filesystem to check
 * return other filesystems mounted to /dev/* in detail
 * set warn & crit default values