updates to apache-log-parser - hostnames, IPv6, empty headers

I've made some changes to make this more useful to me, and hopefully others.  Also, I've tried to include @mipaaa's fixes.

Highlights:
 %h : (updated) handle hostname and IPv6 as well as IPv4 (per apache docs) (fixes #1)
 %b : (added) responseBytes are different than sentBytes (includes headers)
 %{HEADER}i : (updated) - permit blank referrers and agents (fixes #5)
 
 Added getPCRE() function to extract the compiled PCRE for review.
 Updated parse() to include the UNIX Epoch timestamp as 'stamp' when a time is parsed. 

Cheers!