Interrupt Collector and Parser

Changes: (The major ones are really for `/proc/interrupts`)

1. Collector updated:
  * Collector for `cpuusage` and `cpuhz` updated to collect per core rather than aggregated.
  * Collector for `top` updated to have `-c` flag so can see command used to generate process.
  * Collector for `/proc/interrupts` added so can get interrupts per core and IRQs.
  * Collector for `netstat -s` added to collect `netstat` statistics.
2. Parser Metric for `/proc/interrupts`.
3. Added log example for `/proc/interrupts` with a configuration file example.
4. Updated example logs for `sar.cpuusage.out` and `sar.cpuhz.out` to be per core now.

Its for long term maintenance. Let's say we are no longer able to just check for the string 'CPU' in the line to denote if its a header line or not (could happen for many reasons). Then, we will have to find out all the places where we are doing this check and change all of them (prone to errors). If there is one place we do this instead, then its easy to change and maintain it long term. 

Its not a big deal, but a good idea to do it.