[added] Fallback to /proc/cpuinfo...

To grab cpu frequency if sysfs is not supported

This is for Atom cpus which atm show at 0.00Mhz in sysinfo since they dont support the current method.

Thank you @notspiff for this fix.

Before and after screenshot (tested before pr'ing)

![capture](https://cloud.githubusercontent.com/assets/3521959/3966148/d0b493e4-279f-11e4-87b3-9ed5b719f1b1.JPG)