[Bugfix] Port ExecShield checks to RHEL7 and Fedora

- Enable for Fedora
- Fixes #59
[Bugfix] Use ExecShield in OCIL clause

- Reference OS (RHEL7, etc.) with architecture (64-bit, etc.)
- Use ExecShield in OCIL clause
Merge pull request #308 from redhatrises/execshield_port

[Bugfix] Port ExecShield checks to RHEL7 and Fedora