"RHEL6" => "RHEL 6" naming scheme

Noticed the User Guide incorrectly had "RHEL6," which should be "RHEL 6" per Red Hat's syntax guides.
Removing whitespace in primary README

Removing whitespace line in README file
Updated README to reflect move to GitHub

Added GitHub URL to README file
Created OVAL for aide_periodic_cron_checking

Adds OVAL for aide_periodic_cron_checking.

Original patch by Gabe Alford, modified by swells to:
- Reset signoff to Gabe
- Place OVAL in shared
- Setup symlinks
Added bash remediation for aide_periodic_cron_checking
Merge pull request #1 from OpenSCAP/master

rebase
Merge branch 'master' into crontab_oval
Merge pull request #13 from shawndwells/aide_periodic_cron_checking

Aide periodic cron checking