Add sensor specific rule feature

Note:  This feature change requires the existence of the UNIVERSAL_RULES=(true|false) variable in /etc/nsm/securityonion.conf

If UNIVERSAL_RULES=true on the sensor in a distributed deployment the behavior remains the same as the current behavior.

If UNIVERSAL_RULES=false on the sensor in a distributed deployment rule update will scp downloaded compressed rules from the master local to the sensor's /tmp dir and then kicks off a local run of pulledpork (with a -n to prevent additional download) allowing for sensor specific enable/disable/drop/etc pulledpork configurations.

To ensure all compressed rules are pulled over it checks the pulledpork.conf for enabled rule_url values, pulls the rule_file portion of the line out and replaces all instances of (.) with (*.) which has no effect for most files but will match any potential VRT rule since Sourcefire includes the snort version in the output file name.
Added UNIVERSAL_RULES Value

I believe we are on the same page on the non-invasive change, the previously proposed commit defaults to the current behavior, that is to say UNIVERSAL_RULES=true equals business as usual, UNIVERSAL_RULES=false equals scp compressed rules.

What I didn't account for is a securityonion.conf that does not have UNIVERSAL_RULES defined at all.  This is now fixed and sets UNIVERSAL_RULES to true by default and only if it exists in securityonion.conf and set to false will the added feature kick in.
Variable Renaming
Remote PulledPork conf read and error/warnings added

It is now pulling the rule_urls from the master pulledpork.conf.  I also do a quick len check on master vs local and print applicable error/warning messages.

Thoughts?
Merge pull request #1 from chriswhitehat/patch-1

Add sensor specific rule feature