IDS roles

## New Roles
### AIDE
http://aide.sourceforge.net/
This role installs AIDE with mostly default settings, and instructs it to scan the filesystem for changes.  A nightly cron job scans for filesystem changes, and emails unexpected changes to the email address identified in AIDE_REPORT_EMAIL (default: root)

### Snort  
https://www.snort.org/
This role installs snort and oinkmaster and configures oinkmaster to download the latest snort rules from snort.org once on startup, and again on a nightly basis. Events detected by snort are sent to syslog.