porting sysctl_kernel_randomize_va_space to RHEL7

OVAL works the same in 7 as in 6; moved to /shared/oval/ directory

```
# cat /etc/redhat-release ; pwd
Red Hat Enterprise Linux Server release 7.0 (Maipo)
/home/dave/scap-security-guide/RHEL/6/input/checks

# sysctl -w kernel.randomize_va_space=0
kernel.randomize_va_space = 0

# ./testcheck.py sysctl_kernel_randomize_va_space.xml 
Evaluating with OVAL tempfile : /tmp/sysctl_kernel_randomize_va_spaceTB28YZ.xml
Writing results to : /tmp/sysctl_kernel_randomize_va_spaceTB28YZ.xml-results
Definition oval:scap-security-guide.testing:def:100: false
Evaluation done.

# sysctl -w kernel.randomize_va_space=2
kernel.randomize_va_space = 2

# ./testcheck.py sysctl_kernel_randomize_va_space.xml 
Evaluating with OVAL tempfile : /tmp/sysctl_kernel_randomize_va_space_kdjUW.xml
Writing results to : /tmp/sysctl_kernel_randomize_va_space_kdjUW.xml-results
Definition oval:scap-security-guide.testing:def:100: true
Evaluation done.
```