Driver openzlib rhel6 support

This is a first set ot enhancements for OpenVZ VPS driver for work with latest RHEL6 OpenVZ kernel. I added there a one extra function called checkIfRHEL6Kernel() which read /proc/version file and match the kernel version number. 
When the 2.6.32 kernel is detected then driver will set a proper value for physpages. 
The same happened in vpsInfo() function but instead of setting something we are reading a different value from /proc/user_beancounters. Current and max memory is provided by physpages.